Copper oxide solar cell. Copper oxide solar cell * KYOKUSHO.COM

US20140060639A1. Copper oxide core/shell nanocrystals for use in photovoltaic cells. Google Patents

Publication number US20140060639A1 US20140060639A1 US13/828,320 US201313828320A US2014060639A1 US 20140060639 A1 US20140060639 A1 US 20140060639A1 US 201313828320 A US201313828320 A US 201313828320A US 2014060639 A1 US2014060639 A1 US 2014060639A1 Authority US United States Prior art keywords core shell nanocrystal type semiconductor copper oxide Prior art date 2012-08-31 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Abandoned Application number US13/828,320 Inventor Eitan Chaim Zeira Wolfgang Adam Mack, Jr. Molly DOYLE Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) OneSun LLC Original Assignee OneSun LLC Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) 2012-08-31 Filing date 2013-03-14 Publication date 2014-03-06 Priority claimed from US201261696049P external-priority 2013-03-14 Application filed by OneSun LLC filed Critical OneSun LLC 2013-03-14 Priority to US13/828,320 priority Critical patent/US20140060639A1/en 2013-08-28 Priority to PCT/US2013/057145 priority patent/WO2014036179A2/en 2014-03-06 Publication of US20140060639A1 publication Critical patent/US20140060639A1/en 2014-05-14 Assigned to OneSun, LLC reassignment OneSun, LLC ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: MACK, WOLFGANG ADAM, JR., ZEIRA, EITAN CHAIM, DOYLE, Molly Status Abandoned legal-status Critical Current

Images

Classifications

H — ELECTRICITY
H01 — ELECTRIC ELEMENTS
H01L — SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
H01L31/00 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
H01L31/0248 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
H01L31/0256 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
H01L31/0264 — Inorganic materials
H01L31/032 — Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272. H01L31/0312

H — ELECTRICITY
H01 — ELECTRIC ELEMENTS
H01L — SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
H01L31/00 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
H01L31/0248 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
H01L31/0352 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
H01L31/035209 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures
H01L31/035218 — Semiconductor devices sensitive to infra-red radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures the quantum structure being quantum dots

H — ELECTRICITY
H01 — ELECTRIC ELEMENTS
H01G — CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
H01G9/00 — Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
H01G9/20 — Light-sensitive devices
H01G9/2027 — Light-sensitive devices comprising an oxide semiconductor electrode
H01G9/2036 — Light-sensitive devices comprising an oxide semiconductor electrode comprising mixed oxides, e.g. ZnO covered TiO2 particles

H — ELECTRICITY
H10 — SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
H10K — ORGANIC ELECTRIC SOLID-STATE DEVICES
H10K85/00 — Organic materials used in the body or electrodes of devices covered by this subclass
H10K85/10 — Organic polymers or oligomers
H10K85/111 — Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
H10K85/113 — Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
H10K85/1135 — Polyethylene dioxythiophene [PEDOT]; Derivatives thereof

Y — GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y02 — TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
Y02E — REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
Y02E10/00 — Energy generation through renewable energy sources
Y02E10/50 — Photovoltaic [PV] energy
Y02E10/542 — Dye sensitized solar cells

Abstract

The present application relates to a copper oxide nanocrystal with a cupric oxide (CuO) shell surrounding a cuprous oxide (Cu2O) core. The copper oxide core/shell nanocrystals may be used as photo-absorbers in photovoltaic cells. The copper oxide core/shell nanocrystals form a p-type semiconductor layer that coats and fills the interstitial gaps of the n-type semiconductor mesoporous structure in a photovoltaic cell. The n-type semiconductor layer may include, for example, titanium dioxide (TiO2) particles.

Description

This application claims the benefit of U.S. provisional patent application Ser. No. 61/696,049, filed Aug. 31, 2012, the disclosure of which is hereby incorporated by reference in its entirety.

The present disclosure relates generally to photovoltaic devices, and more specifically to the use of copper oxide core/shell nanocrystals in photovoltaic cells (e.g., solar cells) or other cells (e.g., silicon cells).

Photovoltaic cells, such as solar cells, have been the FOCUS of research for many years. See Dittrich et al., “Concepts of Inorganic Solid-State Nanostructured Solar Cells.” Solar Energy Materials Solar Cells 95 (2011): 1527-1536. Current devices typically reach, at best, an average efficiency of 7%. Recently, a higher efficiency of about 10% has been achieved through the use of high mobility, low Band gap, and soluble CsSnI crystals as the hole conductor/absorber. See Chung et al., “All Solid-State Dye-Sensitized Solar Cells with High Efficiency.” Nature 485 (2012). This material, however, is unstable in air.

Other materials have also been considered for use as the photovoltaic absorber. For example, previous attempts to use Cu2O as a photovoltaic absorber have resulted in low current densities due to recombination at grain boundaries within the copper oxide layer. See Bugarinovic et al., “Solar Cells-New Aspects and Solutions; Cuprous Oxide as an Active Material for Solar Cells.” InTech, Rijeka, 2011; B. P. Rai, “Cu2O Solar Cells: A Review”, Solar Cells 25/3 (1988): 265-272; Atwater et al., “Thin, Free-Standing Cu2O Substrates via Thermal Oxidation for Photovoltaic Devices.” 38 th IEEE Photovoltaics Specialist Conference, IEEE (2012).

Thus, what is needed in the art is a material that can be used as an absorber in photovoltaic devices, such as solar cells, that has high mobility and high stability.

The present disclosure addresses this need by providing copper oxide core/shell nanocrystals that have high mobility and high stability, for use as an absorber in photovoltaic devices (e.g., solar cells) and other devices (e.g., silicon cells).

In one aspect, provided is a nanocrystal that includes a core made up of cuprous oxide (Cu2O), and a shell made up of cupric oxide (CuO). The shell may have a thickness between 2 nm and 20 nm. The nanocrystal may have a size between 5 nm and 50 nm. The ratio of the diameter of the core to the thickness of the shell may correspond to the ratio of the hole mobility of the core to the hole mobility of the shell. For example, in one embodiment, the ratio of the diameter of the core to the thickness of the shell is 10-75:0.1-5. In certain embodiments, the ratio of the diameter of the core to the thickness of the shell is between 10:0.1 and 75:0.1, between 15:0.1 and 70:0.1, between 20:0.1 and 60:0.1, between 30:0.1 and 50:0.1, between 10:1 and 75:1, between 15:1 and 70:1, between 20:1 and 60:1, between 30:1 and 50:1, or between 10:1 and 30:1, between 20:1 and 50:1, or between 40:1 and 75:1. In yet other embodiments, the ratio of the diameter of the core to the thickness of the shell is about 10:0.1, about 10:5, about 75:0.1, about 75:5, about 10:1, about 20:1, about 30:1, about 40:1, about 50:1, about 60:1, or about 70:1. The shell may completely or partially surround the core. In one embodiment, the nanocrystal may be substantially spherical. In other embodiments, the nanocrystal may exist in various other shapes and forms including, for example, rods, cubes, disks, pyramids, prisms, and ovoids.

In another aspect, provided is a device that includes a p-type semiconductor layer and a n-type semiconductor layer. The p-type semiconductor layer includes a plurality of nanocrystals, in which each nanocrystal has a core made up of Cu2O, and a shell made up of CuO. The n-type semiconductor layer includes a plurality of particles selected from, for example, titanium dioxide particles, zinc oxide particles, zirconium oxide particles, and any combinations thereof. In one embodiment, the device may further include a metal electrode; and a hole injection layer, wherein the hole injection layer is between the metal cathode and the p-type semiconductor layer. The hole injection layer may, for example, be made up of poly(3,4-ethylenedioxythiophene) (PEDOT), carbon black, or a combination thereof. In another embodiment, the device may further include a polymeric substrate; a transparent conductor; and an electron injection layer. The transparent conductor is coated on the polymeric substrate. The electron injection layer is between the n-type semiconductor layer and the transparent conductor, and may, for example, be made up of titanium oxide. The device described herein has an average efficiency of at least 7%. In some embodiments, the device may be a photovoltaic cell.

The present disclosure can be best understood by reference to the following description taken in conjunction with the accompanying figures, in which like parts may be referred to by like numerals.

FIG. 2 depicts part of an exemplary photovoltaic cell with copper oxide core/shell nanocrystals filling the interstitial spaces of a titanium dioxide mesoporous structure;

FIG. 3 depicts an exemplary interface between copper oxide core/shell nanocrystals and titanium dioxide particles;

The following description sets forth numerous specific configurations, parameters, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention, but is instead provided as a description of exemplary embodiments.

Provided herein are copper oxide core/shell nanocrystals for use in photovoltaic devices, such as solar cells. These nanocrystals have a cuprous oxide (Cu2O) core, and a cupric oxide (CuO) shell that at least partially surrounds the core. This Cu2O/CuO structure benefits from the high mobility of Cu2O and the stability of CuO.

Cu2O is a non-toxic, low cost, earth abundant material with an ideal Band gap and a long minority carrier diffusion length, making it a desirable absorber for solar cells. However, as discussed above, Cu2O as a photovoltaic absorber has resulted in low current densities due to recombination at grain boundaries within the copper oxide layer. The presence of a CuO layer surrounding the Cu2O material can protect high mobility cuprous oxide from reduction, but also reduces recombination and increases current density in a bilayer photo-electrochemical cell. The Cu/Cu2O interface forms a Schottky barrier that diminishes charge transport and result in low conversion efficiency solar cells. CuO on the other hand is a more stable form of copper oxide, but has low mobility and cannot be used as a hole transport layer alone.

While CuO has been observed to naturally form on the surface of Cu2O, the layer thickness of this “native” oxide is typically less than 1 nm. See e.g., Applied Surface Science 255 (2008) 2730-2734; A. Soon et al., Surface Science 601 (2007) 5809-5813. Cu2O particles with a native CuO layer on the surface do not offer the passivation and charge transfer that would be suitable for use in photovoltaic applications. Attempts to further oxidized the Cu2O typically yields a mixed phase that occurs in the bulk, which also renders such material unsuitable for use in photovoltaic applications. See A. O. Musa, T. Akomolafe and M. J. Carter, Sol. Energy Mater. Sol. Cells, vol. 51, pp. 305-316, 1998. The presence of a mixed phase Cu2O/CuO has been shown to quench the photovoltaic effect. See e.g., S. Sunkara, et al., Catal. Today (2012).

In contrast to the Cu2O materials known in the art, provided herein are Cu2O nanocrystals with a CuO shell having a thickness of between 2 nm and 20 nm. In some embodiments, the Cu2O/CuO particles typically have a size between 5 nm and 50 nm. The use of such copper oxide core/shell nanocrystals with the specific CuO shell thickness unexpectedly improves both stability and efficiency of resultant photovoltaic cells.

With reference to FIG. 1. exemplary nanocrystal 100 has core 102 surrounded by shell 104. A nanocrystal core surrounded by a shell is referred to as a “core/shell” nanocrystal. The term “core” refers to the inner portion of the nanocrystal. Core 102 is made up of Cu2O. The core may contain impurities. For example, a dopant can be placed within the material forming the core. The term “shell” refers to a second material that surrounds the core. Shell 104 is made up of CuO. In certain embodiments, shell 104 may further include one or more materials that are intrinsically semiconductors and stable. For example, the shell may further include nickel oxide, tungsten oxide, aluminum oxide, vanadium oxide, zirconium oxide, or any combinations thereof.

While FIG. 1 depicts shell 104 completely surrounding core 102, it should be understood that in other exemplary embodiments, the shell may partially surround the core. Thus, a shell may be “complete”, indicating that the shell completely surrounds the outer surface of the core. Alternatively, a shell may be “incomplete”, indicating that the shell partially surrounds the outer surface of the core.

The size of a nanocrystal depends on the diameter of the core and the thickness of the shell. With reference to FIG. 1. nanocrystal 100 has size 110, with core 102 having diameter 108 and shell 104 having thickness 106. For example, a spherical copper oxide nanocrystal may have an overall size of 10 nm, with a 6 nm diameter core of Cu2O surrounded by a 2 nm thick shell of CuO. In certain embodiments, the nanocrystal has a size between 5 nm and 50 nm, between 5 nm and 40 nm, between 5 nm and 30 nm, between 5 nm and 20 nm, between 5 nm and 20 nm, between 5 nm and 10 nm, between 5 nm and 7 nm, between 10 nm and 50 nm, between 10 nm and 40 nm, between 10 nm and 30 nm, between 10 nm and 20 nm, between 10 nm and 20 nm, between 15 nm and 50 nm, between 15 nm and 40 nm, between 15 nm and 30 nm, or between 15 nm and 20 nm.

Reference to “between” two values or parameters herein includes (and describes) embodiments that include the stated value or parameter per se. For example, description referring to “between x and y” includes description of “x” and “y”.

When the core has a spherical shape, as depicted in FIG. 1. the term “diameter” is as commonly understood. It should be understood, however, that the core (and hence the nanocrystal) may exist in a variety of shapes including, for example, rods, cubes, disks, pyramids, prisms, and ovoids. When the core has a non-spherical shape, the term “diameter” refers to a radius of revolution in which the entire non-spherical core would fit.

The size and shape of nanocrystals may be varied depending on the conditions (e.g., pH, temperature) used to prepare the nanocrystals. See e.g., Ke Xin Yao et al., “Synthesis, Self-Assembly, Disassembly, and Reassembly of Two Types of Cu2O Nanocrystals Unifacted with 001or Planes”, J. Am. Chem. Soc. 2010, 132, 6131-6144; Jingqu Tian et al., “One-pot green hydrothermal synthesis of CuO—Cu2O—Cu nanorod-decorated reduced grapheme oxide composites and their application in photocurrent generation”, Catal. Sci. Technol. 2012; U.S. Pat. No. 7,851,338; U.S. Pat. No. 7,825,405; U.S. Pat. No. 7,402,832.

It should be understood that the thickness of the shell may vary. In some embodiments, the shell may have a thickness of between 2 nm and 20 nm, between 3 nm and 20 nm, between 4 nm and 20 nm, between 5 nm and 20 nm, between 6 nm and 20 nm, between 7 nm and 20 nm, between 8 nm and 20 nm, between 9 nm and 20 nm, between 10 nm and 20 nm, between 11 nm and 20 nm, between 12 nm and 20 nm, between 13 nm and 20 nm, between 14 nm and 20 nm, between 15 nm and 20 nm, between 5 nm and 15 nm, or between 5 nm and 10 nm. In some embodiments, as depicted in FIG. 1. the shell may have a uniform thickness. In other embodiments, the shell may have a non-uniform thickness. For example, clumps of shell material may form on the surface of the core.

The thickness of the CuO shell may be selected to provide a balance between protecting the Cu2O core from further reduction reactions and avoiding creating too much resistance. This balance can be described by the ratio of the diameter of the core to the thickness of the shell. In some embodiments, this ratio may correspond to the ratio of the hole mobility of the core to the hole mobility of the shell. The “hole mobility” describes the speed at which electrons can move through a semiconductor material when pulled by an electric field. Hole mobility may be expressed in units of cm2/(V.s). For example, in one exemplary embodiment, if the Cu2O core has a hole mobility of 10 cm2/(V.s) and the CuO shell has a hole mobility of 1 cm2/(V.s), the ratio of the diameter of the core to the thickness of the shell is 10 to 1 (i.e., a 1 nm thick shell on a 10 nm diameter core). The ratio of the diameter of the core to the thickness of the shell may vary. In certain embodiments, the ratio of the diameter of the core to the thickness of the shell is 10-75:0.1-5. The hole mobilities of the core and the shell may vary depending on the methods in which the core and the shell are prepared. Factors that affect hole mobility may include, for example, the doping level, as well as the pH and temperature conditions at which the core and the shell are prepared.

Additionally, doping may be employed to minimize the valence Band offset between the core and shell layers. Particle-to-particle charge conduction is predominantly holes as the valence Band of CuO/Cu2O match, while the gap of conduction bands excludes electronic conduction. CuO typically has a valence Band of 5.42 eV, whereas Cu2O has a valence Band of 5.25 eV, which make particle-to-particle hole conduction feasible. The closer these valence bands are to each other, the less resistive loss will likely occur.

The copper oxide core/shell nanocrystals described herein can be synthesized by any suitable methods. For example, in one embodiment, Cu2O nanocrystals are provided or prepared, which can then be calcined at 400° C. for 1 hour in ambient conditions to form a CuO surface surrounding at least a portion of the Cu2O nanocrystal. See e.g., Z. Zhang and P. Wang. “Highly Stable Copper Oxide Composite as an Effective photocathode for Water Splitting via a Facile Electrochemical Synthesis Strategy.” Journal of Materials Chemistry 22 (2012): 2456. The resulting nanocrystal with a Cu2O core and CuO shell can then be subsequently re-grinded in a bead mill to break up agglomerates. It should be understood that other suitable methods may also employed to achieve a controlled oxidation of the Cu2O nanocrystal to form a CuO surface surrounding at least a portion of the Cu2O nanocrystal. Such methods may include, for example, the addition of controlled amounts of mild oxidants such as trimethylamino N-oxide or pyridine N-oxide.

Methods and techniques are known in the art to prepare copper oxide particles using flame spray pyrolysis. See e.g., Chiang, C-Y et al, Intl. J. of Hydrogen Energy 37 (2012) 4871-4879. In certain embodiments, copper oxide core/shell nanocrystals described herein can be produced in a two step flame spray pyrolysis process, where first reducing conditions are used to create the bulk Cu2O phase out of a liquid metal precursor spray. The growing particles are subsequently exposed to a more oxidizing condition to control the growth of the CuO phase of the outer shell. The flow rate of the central spray and the flow rate of the oxygen/methane gas can affect the thickness of the CuO shell formed. For example, to obtain a CuO shell having a thickness of between 2 nm and 20 nm, the ratio of oxygen flow rate to precursor flight rate may be between 2:1 and 3:1. Further, the total flight time of the particle can determine the overall size of the particle. For example, to obtain a nanocrystal having a size between 5 nm and 50 nm, the distance between the spray and filter that collects the particle may be between 5 cm to 1 ft.

The size, shape and distribution of the copper oxide nanocrystals may be determined by any suitable method known in the art. For example, laser scattering or a coulter counter may be used to determine particle dispersion. Atomic form microscopy may be used to determine porosity and density of particles deposited on a substrate.

The copper oxide core/shall nanocrystals described herein can be used in photovoltaic devices. Such photovoltaic devices may include, for example, dye-sensitized solar cells (DSSC) or silicon cells. See e.g., B. E. Hardin, et al., “The renaissance of dye-sensitized solar cells”, Nature Photonics, Vol. 6, March 2012: 162-169; R. Motoyoshi, et al., “Fabrication and Characterization of Copper System Compound Semiconductor Solar Cells”, Adv. in Mat. Sc. and Eng., Vol. 2010, Article ID 562842 (11 pages). For example, the copper oxide core/shall nanocrystals may be used in DSSCs as a photovoltaic absorber and/or an interface layer to provide the appropriate Band energy structure between the copper oxide photon absorber and the n-type semiconductor (e.g., TiO2 semiconductor).

The use of the copper oxide nanocrystals described herein increases the efficiency of a photovoltaic device. In some embodiments, the device has an average efficiency of at least 7%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, or at least 50%. In some embodiments, the device has an average efficiency of between 7% and 90%, between 7% and 80%, between 10% and 50%, between 10% and 30%, or between 20% and 70%. As used herein, “efficiency” refers to the percentage of photons converted to electrons. Efficiency may be determined by measuring the level of power, which may be expressed in mW/cm2. For example, if the sun produces 100 mW/cm2 and the device produces 15 mW/cm2, the device can be described as having an efficiency of 15%.

With reference to FIG. 4. exemplary photovoltaic cell 400 includes polymeric substrate 402, transparent conductor 404, electron injection layer 406, n- type semiconductor 408, p- type semiconductor 410, hole injection layer 412, and electrode 414. Each component of photovoltaic cell 400 is described in further detail below. It should be understood that, in other exemplary photovoltaic cells, certain of these components may be omitted or replaced with other suitable components, or additional components may be present in the photovoltaic cells.

Polymeric substrate 402 serves as the base for all the subsequent coated layers. In some embodiments, the polymeric substrate may have a dimensional stability of less than 1% shrinkage at 150° C.

Transparent conductor 404 provides the ability for light to go through to the cell, while serving as an electrical conductor to collect the electrons generated in the cell at the anode. In some embodiments, the transparent conductor layer may have at least 85% transmission in the visible range. In other embodiments, the transparent conductor may have a sheet resistance of less than 10Ω/□.

Electron injection layer 406 (also known as an electron interface layer or a hole blocking layer) is an n-type electron transport layer that can isolate the transparent conductor from inadvertent contact with p- type semiconductor 410. In some embodiments, the electron injection layer electronically matches the conduction Band energy of the n-type semiconductor with that of the transparent conductor. For example, in one embodiment, the n-type semiconductor with TiO2 particles may have a Band energy of 4.2 eV, the electron injection layer with titanium oxide (TiOx) particles may have a Band energy of 4.4 eV, and the transparent conductor made up of indium tin oxide (ITO) may have a Band energy of 4.7 eV.

N- type semiconductor 408 serves to grab electrons from p- type semiconductor 410, and transport the electrons to transparent conductor 404. In some embodiments, the n-type semiconductor is made up of a high Band gap electron transport material with a valence Band energy level that is more electronegative than the conduction Band of the p-type semiconductor layer. In one embodiment, a high Band gap may refer to greater than 3 eV. In another embodiment, more electronegative may refer to at least 0.3 eV. In yet other embodiments, the material making up the n-type semiconductor layer may also have electron mobility in excess of 50 cm2/(V.s).

In one embodiment, the n-type semiconductor includes a plurality of TiO2 particles. Other suitable materials may be used for the n-type semiconductor including, for example, zinc oxide particles and zirconium oxide particles. These particles typically form a mesoporous structure.

The particles making up the n-type semiconductor may have varying sizes. The particles within a given layer may be of the same size or of different sizes. The “size” of particle in the n-type semiconductor refers to the diameter of the particle. When the particle has a spherical shape, the term “diameter” is as commonly understood. The particle may, however, exist in a variety of shapes including, for example, rods, cubes, disks, pyramids, prisms, and ovoids. When the particle has a non-spherical shape, the term “diameter” refers to a radius of revolution in which the entire non-spherical particle would fit.

The plurality of particles making up the n-type semiconductor may have a distribution of sizes. For example, in one embodiment, the size of a plurality of particles may refer to the average size of the particles. For example, when the particles are TiO2 particles, in some embodiments, the particles may have a size between 100 nm and 200 nm.

P- type semiconductor 410 serves to create electron hole pairs, donate electrons to n- type semiconductor 408 and conduct holes to electrode 414. In some embodiments, the p-type semiconductor is made up of low Band gap material with high hole mobility. In one embodiment, low Band gap refers to less than 2 eV. In another embodiment, high hole mobility refers to at least 25 cm2/(V.s).

In one embodiment, the n-type semiconductor includes a plurality of copper oxide nanocrystals described herein. Specifically, each nanocrystal has a core made up of Cu2O and a shell made up of CuO.

The plurality of copper oxide nanocrystals may have a distribution of sizes. For example, in one embodiment, the size of a plurality of copper oxide nanocrystals may refer to the average size of the nanocrystals. The size of the copper oxide nanocrystals in the p-type semiconductor layer may be proportional to the size of the particles in the n-type semiconductor layer. For example, in one embodiment where the n-type semiconductor layer is made up of TiO2 particles, the size of the copper oxide nanocrystals is between ⅓ and ⅕ the size of the TiO2 particles.

With reference to FIG. 2. in one exemplary embodiment, copper oxide nanocrystals 204 coats the top surface of TiO2 mesoporous structure 202, and fills the interstitial spaces in TiO2 mesoporous structure 202. The copper oxide nanocrystals may completely coat the top surface of the TiO2 mesoporous structure, as depicted in FIG. 2. In other embodiments, however, the copper oxide nanocrystals may partially coat the top surface of the TiO2 mesoporous structure.

The copper oxide nanocrystals may fill between 0% and 100% of the void in the n-type semiconductor. In some embodiments, the copper oxide nanocrystals fill at least 20%, at least 30%, at least 40%, at least 50%, between 20% and 100%, or between 20% and 40% of the void in the n-type semiconductor. Various techniques and methods may be employed to more fully fill the interstitial spaces in the n-type semiconductor. For example, in one embodiment, a copper (II) acetate solution may be disposed on the n-type semiconductor, followed by thermal conversion to form CuO.

Additionally, in some embodiments, an interface layer may be coated on some of the particles of the n-type semiconductor to afford better charge injection between the p-type and n-type semiconductors. With reference to FIG. 3. TiO2 particle 302 in contact with copper oxide nanocrystal 306 may be partially coated at the interface with layer 304. In some embodiments, this layer may be made up of poly(3,4-ethylenedioxythiophene) (PEDOT), carbon black, or a combination thereof.

Hole injection layer 412 (also known as a hole interface layer) serves to transfer the holes from the p-type semiconductor layer to electrode 414. The hole injection layer may be made up of a hole conductor with a high work function and a sufficiently high surface energy to enable coating the metal conductor on top of it. For example, the hole conductor has at least 5 eV. Examples of materials suitable for the hole injection layer include poly(3,4-ethylenedioxythiophene) (PEDOT), carbon black, or a combination thereof.

Electrode 414 is a metal electrode or, more specifically, a cathode. The electrode may be a solid metal or metal flake ink that collects the holes. Electrode 402 may have high conductivity to conduct the holes over a long distance from cell to cell and out of the module to do work. For example, electrode 402 may have a sheet resistance of at least 1Ω/□.

Photovoltaic device 400 may include other components commonly known in the art needed to make a functioning device. For example, other components may include cell-to- cell interconnect 416. Additionally, gap 418 exists between cells to enable cell-to-cell series connection. Coated insulators 420 and 422 separate cells.

Various methods and techniques may be employed to construct a photovoltaic device, such as a photovoltaic cell, with the copper oxide core/shell nanocrystals described herein. For example, in one embodiment, an indium tin oxide (ITO) coated film (e.g., OC36 from Technimet) is first provided. Then, 0.1% titanium isopropoxide in ethanol and water is prepared, coated on top of the ITO coated film, and allowed to dry at 120° C. for 3 minutes. The resulting stack is coated by 20% solids P25 in isopropyl alcohol (IPA) and a 5 nm dispersion from Solaronix, which is then dried at 120° C. for 5 minutes. To this stack is coated a dispersion of the copper oxide cores/hell nanoparticle (as described above) in water, which is cured at 120° C. for 5 minutes, coated with PEDOT s305 diluted with ethanol, and dried at 120° C. for 5 minutes. A silver top electrode is the printed, for example using Sun chemicals SOL305 baked at 120° C. for 10 minutes.

In other exemplary embodiments, the copper oxide core/shell nanocrystals described herein may be coated a top a standard silicon cell in a tandem cell-type architecture to extend the absorption spectrum of the resultant device, and therefore enhance its photovoltaic conversion efficiency. Such a tandem device, for example, would comprise a standard p/n junction silicon cell with the addition of the copper oxide core/shell nanocrystal layer coated on top, followed by the top electrode fingers or grid metal conductor that collect the charges.

For example, in one embodiment, the copper oxide core/shell nanocrystals described herein may be coated on top of a first junction, e.g., a standard silicon junction, that is mainly absorbing light in a wavelength range that is different than the wave length range absorbed by the second junction that is employing a copper oxide core/shell nanocrystal absorbing layer. By employing a recombination layer structure between the two junctions of the tandem solar cell (e.g., a tunnel junction) both Voc and Jsc can be optimized in a way that enhances the photovoltaic conversion efficiency, compared to the corresponding single-junction solar cells’ performance. For instance, such a tandem solar cell may includes a standard silicon p/n junction with a thin matching tunnel diode of type Esaki diode deposited or coated on top of the silicon p/n junction. Consecutively, a p-type copper oxide core/shell layer can be coated, which may be followed by an n-type large Band-gap window layer such titania or zinc oxide. Finally, the top electrode is deposited, which may consist of metal fingers or a metal grid that collect the charges.

Claims ( 15 )

a shell comprising cupric oxide (CuO), wherein the shell surrounds at least a portion the core, and wherein the shell has a thickness between 2 nm and 20 nm, and

The nanocrystal of claim 1. wherein the core has a diameter, wherein the core and the shell each independently have a hole mobility, and wherein the ratio of the diameter of the core to the thickness of the shell corresponds to the ratio of the hole mobility of the core to the hole mobility of the shell.

The nanocrystal of claim 1. wherein the core has a diameter, and wherein the ratio of the diameter of the core to the thickness of the shell is 10-75:0.1-5.

a p-type semiconductor layer, wherein the p-type semiconductor layer comprises a plurality of nanocrystals, wherein each nanocrystal comprises a core comprising cuprous oxide (Cu2O), and a shell comprising cupric oxide (CuO); and

a n-type semiconductor layer, wherein the n-type semiconductor layer comprises a plurality of metal oxide particles.

The device of claim 7. wherein the metal oxide particles are selected from the group consisting of titanium dioxide particles, zinc oxide particles, zirconium oxide particles, and any combinations thereof.

a hole injection layer, wherein the hole injection layer is between the metal cathode and the p-type semiconductor layer.

The device of claim 10. wherein the hole injection layer comprises poly(3,4-ethylenedioxythiophene) (PEDOT), carbon black, or a combination thereof.

an electron injection layer, wherein the electron injection layer is between the n-type semiconductor layer and the transparent conductor.

US13/828,320 2012-08-31 2013-03-14 Copper oxide core/shell nanocrystals for use in photovoltaic cells Abandoned US20140060639A1 ( en )

Priority Applications (2)

Application Number Priority Date Filing Date Title

US13/828,320 US20140060639A1 ( en )	2012-08-31	2013-03-14	Copper oxide core/shell nanocrystals for use in photovoltaic cells
PCT/US2013/057145 WO2014036179A2 ( en )	2012-08-31	2013-08-28	Copper oxide core/shell nanocrystals for use in photovoltaic cells

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title

US201261696049P	2012-08-31	2012-08-31
US13/828,320 US20140060639A1 ( en )	2012-08-31	2013-03-14	Copper oxide core/shell nanocrystals for use in photovoltaic cells

Family Applications (1)

Application Number Title Priority Date Filing Date

US13/828,320 Abandoned US20140060639A1 ( en )

2012-08-31

2013-03-14

Copper oxide core/shell nanocrystals for use in photovoltaic cells

Cited By (10)

Cited by examiner, † Cited by third party

Publication number Priority date Publication date Assignee Title

US20150144195A1 ( en )	2013-11-26	2015-05-28	Michael D. IRWIN	Perovskite and other solar cell materials
WO2015153831A1 ( en )	2014-04-04	2015-10-08	Tufts University	Cupric oxide semiconductors
WO2015170987A1 ( en )	2014-05-09	2015-11-12	Universiteit Leiden	Process for forming a leaf-shaped nanoparticulate material, an electrochemical cell and a process to convert water
WO2017031021A1 ( en )	2015-08-14	2017-02-23	Massachusetts Institute Of Technology	Perovskite solar cells including semiconductor nanomaterials
CN107326383A ( en )	2017-05-19	2017-11-07	浙江大学	A kind of cuprous oxide base heterojunction photocathode and preparation method thereof
JP2018088480A ( en )	2016-11-29	2018-06-07	株式会社豊田中央研究所	Solar battery, solar battery module, and method of manufacturing solar battery
US10913056B2 ( en )	2017-07-31	2021-02-09	Honda Motor Co., Ltd.	Method for synthesis of copper/copper oxide nanocrystals
CN112863875A ( en )	2020-11-26	2021-05-28	南昌航空大学	Preparation method of core-shell structure tin oxide photo-anode dye-sensitized solar cell
CN112978783A ( en )	2021-02-19	2021-06-18	中国科学技术大学	Cuprous oxide nano material, preparation method and application thereof
US11339487B2 ( en )	2019-02-28	2022-05-24	Honda Motor Co., Ltd.	Synergistic effects of multi-faceted CU2O nanocrystals for electrochemical CO2 reduction

Families Citing this family (1)

Cited by examiner, † Cited by third party

Publication number Priority date Publication date Assignee Title

CN105116030B ( en )

2015-07-27

2017-11-03

中国海洋大学

A kind of Cu2Nuclear-shell structured nano-composite materials of O@CuO half and preparation method thereof

Citations (3)

Cited by examiner, † Cited by third party

Publication number Priority date Publication date Assignee Title

WO2011005013A2 ( en )	2009-07-06	2011-01-13	한양대학교 산학협력단	Solar cell using p-i-n nanowires
US20110227047A1 ( en )	2010-03-22	2011-09-22	National Cheng Kung University	Organic photoelectric semiconductor device and method for fabricating the same
US20120098028A1 ( en )	2010-10-22	2012-04-26	Kabushiki Kaisha Toshiba	Photoelectric conversion element and manufacturing method thereof

Patent Citations (4)

Cited by examiner, † Cited by third party

Publication number Priority date Publication date Assignee Title

WO2011005013A2 ( en )	2009-07-06	2011-01-13	한양대학교 산학협력단	Solar cell using p-i-n nanowires
US20120097232A1 ( en )	2009-07-06	2012-04-26	Industry-University Cooperation Foundation, Hanyang University	Solar cell using p-i-n nanowire
US20110227047A1 ( en )	2010-03-22	2011-09-22	National Cheng Kung University	Organic photoelectric semiconductor device and method for fabricating the same
US20120098028A1 ( en )	2010-10-22	2012-04-26	Kabushiki Kaisha Toshiba	Photoelectric conversion element and manufacturing method thereof

Cited By (16)

Cited by examiner, † Cited by third party

Publication number Priority date Publication date Assignee Title

US9136408B2 ( en )	2013-11-26	2015-09-15	Hunt Energy Enterprises, Llc	Perovskite and other solar cell materials
US11024814B2 ( en )	2013-11-26	2021-06-01	Hunt Perovskite Technologies, L.L.C.	Multi-junction perovskite material devices
US20150144195A1 ( en )	2013-11-26	2015-05-28	Michael D. IRWIN	Perovskite and other solar cell materials
US10608190B2 ( en )	2013-11-26	2020-03-31	Hee Solar, L.L.C.	Mixed metal perovskite material devices
US10333082B2 ( en )	2013-11-26	2019-06-25	Hee Solar, L.L.C.	Multi-junction perovskite material devices
US10115847B2 ( en )	2014-04-04	2018-10-30	Trustees Of Tufts College	Cupric oxide semiconductors
WO2015153831A1 ( en )	2014-04-04	2015-10-08	Tufts University	Cupric oxide semiconductors
NL2012787B1 ( en )	2014-05-09	2016-02-24	Univ Leiden	Process for forming a leaf-shaped nanoparticulate material, an electrochemical cell and a process to convert water.
WO2015170987A1 ( en )	2014-05-09	2015-11-12	Universiteit Leiden	Process for forming a leaf-shaped nanoparticulate material, an electrochemical cell and a process to convert water
WO2017031021A1 ( en )	2015-08-14	2017-02-23	Massachusetts Institute Of Technology	Perovskite solar cells including semiconductor nanomaterials
JP2018088480A ( en )	2016-11-29	2018-06-07	株式会社豊田中央研究所	Solar battery, solar battery module, and method of manufacturing solar battery
CN107326383A ( en )	2017-05-19	2017-11-07	浙江大学	A kind of cuprous oxide base heterojunction photocathode and preparation method thereof
US10913056B2 ( en )	2017-07-31	2021-02-09	Honda Motor Co., Ltd.	Method for synthesis of copper/copper oxide nanocrystals
US11339487B2 ( en )	2019-02-28	2022-05-24	Honda Motor Co., Ltd.	Synergistic effects of multi-faceted CU2O nanocrystals for electrochemical CO2 reduction
CN112863875A ( en )	2020-11-26	2021-05-28	南昌航空大学	Preparation method of core-shell structure tin oxide photo-anode dye-sensitized solar cell
CN112978783A ( en )	2021-02-19	2021-06-18	中国科学技术大学	Cuprous oxide nano material, preparation method and application thereof

Legal Events

Owner name: ONESUN, LLC, CALIFORNIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ZEIRA, EITAN CHAIM;MACK, WOLFGANG ADAM, JR.;DOYLE, MOLLY;SIGNING DATES FROM 20140502 TO 20140513;REEL/FRAME:032887/0635

Free format text: ABANDONED.- FAILURE TO RESPOND TO AN OFFICE ACTION

Copper oxide solar cell

To date, numerous attempts have been carried out to provide energy from natural resources. As the petroleum related fuels produce large amount of pollution which had been reported as a big threat to creature life, employing green technique in providing the energy turned to an inevitable approach. Solar energy attracted much attention in reaching green and sustainable energy from natural resources. Emerging photovoltaic properties of materials has introduced an easy and green technique in generating the electricity from sunlight which is an abundant resource worldwide.

Perovskite solar cells emerged as an efficient and low cost solar cell which attracted much attention in absorbing a large portion of sun light to generate electricity. Organometal halide perovskite is an interesting photovoltaic material with an approximate direct optical Band gap, which has numerous advantages like broad range of light absorption from the visible to near infrared spectra with high extinction coefficient and long diffusion length. To date, the certified power conversion efficiency reached to 20.3%. Material selection and engineering for electron transport material (ETM) and hole transport material (HTM) for extracting electron and hole, respectively, from organometal trihalide perovskite absorber has a high impact on perovskite solar cells efficiency. By now, despite the large number of valuable works conducted on improving the perovskite solar cells performance and resolving some challenges such as durability against moisture, the production cost of these devices is high due to the use of some expensive materials (such as Spiro-OMeTAD) in device structures. Hence, in addition of device stability, replacing the expensive materials in fabrication of perovskite solar cells would facilitate reaching these efficient solar cells to market and human life.

Copper based hole transport materials such as CuI and CuSCN attract much attention in fabrication of perovskite solar cells because of their high hole mobility and low cost fabrication methods and materials.

Using metal oxides as both n-type and p-type materials for perovskite solar cells is a future vision and appeal considering their robust behavior, long-term durability, low cost, and importantly environment and market friendly characteristics. Cuprous oxide (Cu2O) with narrow Band gap is promising and environmental-friendly p-type material for absorbing and hole transporting in p-n junction solar cells. over, the respective hole mobility and diffusion length is reported for cuprous oxide structure making this as an appropriate inorganic and low cost HTM for perovskite solar cells.

Here, Cu2O thin film is introduced as a potential new hole transport materials for durable perovskite solar cells (Fig. 1.). Considering the fact that copper oxide is highly sensitive to the mixture of perovskite precursors and their solvents, we proposed an engineered technique of reactive magnetron sputtering in this work. A rotational angular deposition of copper oxide shows a well surface coverage of perovskite layer for high rate of charge extraction (Fig. 1.). Deposition of Cu2O layer on the pinhole-free perovskite layer shows the maximum power conversion efficiency of 8.93% (Fig.1). than 30 days stability of these kinds of perovskite solar cells (Fig. 2.) provides a new vision in enhancing and developing the perovskite solar cells employing cuprous oxide as an inorganic hole transport material.

Bahram Abdollahi Nejand 1. Saba Gharibzadeh 2. Vahid Ahmadi 3 and Hamid Reza Shahverdi 1 1 Nanomaterials Group, Dept. of Materials Engineering, Tarbiat Modares University, Tehran-Iran 2 Department of Physics, Tarbiat Modares University, Tehran-Iran 3 School of Electrical and Computer Engineering, Tarbiat Modares University

Ultrasound generate electricity inside the body Implantable medical devices (IMDs) are highly beneficial to patient health. Concerning rapidly evolving technologies for IMDs, sustainable and reliable powering methods for IMDs is truly essential. They are generally relying…

Sustainable ZnSnO3 nanowires produced by a low-cost solution… Oxide materials, and more specifically, multicomponent oxide materials, have been widely explored in thin-film technology, being the indium-based materials very common. For example, conductive indium-tin oxide (ITO) or semiconductive indium-gallium-zinc…

Sustainable solutions: Tamarind Seed Kernel powder (TKP)… The majority of petroleum-based adhesives applied in the wood industry today, particularly formaldehyde-based adhesives. Their application trend is increasing due to their wide availability, superior bonding, durability, and resistance to…

Chicago data suggests light pollution disrupts animals’… Population growth, economic development, and urbanization mean more ecosystems are lit throughout the night. Ecologists and astronomers, among other concerned folks, have been raising the alarm that “ecological light pollution”…

Strengthening the Paris Agreement by supply-side climate… To reach the Paris Agreement’s goal of keeping global warming well below 2 degrees, much of the world’s deposits of oil, gas and coal must be left permanently in the…

WRGSD: improving reliability and efficiency for coastal… Water-quality response grid-based sampling design (WRGSD) using optimization and multi-factors assessment can reliably detect a variety of the impact of human activities. The sampling design are optimized by clustering and…

Electrodeposited Copper Oxide and Zinc Oxide Core-Shell Nanowire Photovoltaic Cells

Uncertainty in energy capacity, limited fossil fuel resources, and changes in climate predicate a need for increased research and development into alternative and sustainable energy solutions. Solar energy is one solution to this problem and many variations of it exist; however, the majority of them are prohibitively expensive. We propose a low-cost solar energy generation method which is cost-effective both in materials and production. Our solution will utilize cheap, abundant materials as well as lower-cost fabrication methods to produce photovoltaic (PV) cells. Although it is unlikely that the efficiency of such cells will be record-breaking, its low cost should make its price-per-watt-produced competitive, which is one of the most important metrics for the commercialization of any solar technology.

Our design consists of a radial heterojunction comprised of p-type copper oxide and n-type zinc oxide nanowires, which are oxides of earth-abundant materials. The nanowires have a core-shell design to minimize carrier travel distance and maximize junction area. Furthermore, we utilize a wet chemistry fabrication process, making the production of such cells inexpensive, easily scalable and non-demanding in terms of fabrication energy. The process involves growing copper nanowires, oxidizing, plating zinc oxide, and depositing a top contact.

The case for solar

Solar energy is an attractive solution to demanding energy problems because of the amount of energy it can produce, its low maintenance and operating costs, and its clean nature. The sun has the ability to provide more than enough energy to satiate the world’s demands, even accounting for future growth. Once in place, solar panels will continue to provide electricity for decades with minimal human interaction; systems can still operate after 40 years (King, Quintana et al. 2000) and have the potential to last even longer. There are no fuel costs or harmful pollutants during operation, and setup needs only little training.

The amount of energy coming from the sun is greater than any other form of renewable energy. Solar radiation accounts for 173,000 TW of energy, dwarfing all other renewables such as wind and waves at 3600 TW, geothermal energy at over 32 TW, and tidal energy at 3 TW (Da Rosa 2005). Although these numbers do not reflect the amount of electricity able to be produced from their respective sources of energy, it does demonstrate a clear dominance of solar over all other forms of energy.

Solar energy has the potential to supply all of the worlds power needs as demonstrated by Figure 1. If the six black circles were covered in solar panels of only 8% efficiency, 18 TW of energy could be produced (Loster 2010), which is more than the total energy consumption in 2007 of 16.6 TW (U.S. Energy Information Administration 2010). The total land area needed is approximately 910,000 sq. km. (Loster 2010) or about 0.6% of the total land area on earth. It should be noted that many solar cell designs which exceed 8% conversion efficiency have been produced. (Green, Emery et al. 2010)

Although solar photovoltaics have a substantial up-front cost, the operation and maintenance costs are minimal. Since solar cells are solid-state devices and have no moving parts (except in the case of tracking systems), they are highly reliable.

Photovoltaics generate no harmful emissions during use, nor do they produce any noise or unwanted by-products. (Luque and Hegedus 2003) This clean quality as well as the highly modular and scalable nature of the technology makes it an excellent choice for a myriad of power systems. Solar panels can be used by households to provide energy for one’s home, for off grid remote power generation, or for large-scale utility plants. Outside of the manufacturing process, solar panels are very environmentally friendly and do not contribute CO2 to the atmosphere. Utilizing end-of-life recycling and more benign industrial processing will make the technology even more environmentally friendly in the future.

2.1. Solar cell basics

Solar photovoltaic cells are devices which turn radiant energy from the sun directly into electricity. Factors which affect the amount of energy created include the intensity of radiation, the spectral distribution of the radiation, and the specific materials, design, and quality of the solar cell at hand. Most inorganic solar cells, however, work in the same manner and will be described presently.

Electromagnetic radiation (primarily in the visible and near-infrared regions of the spectrum) is emitted from the sun and absorbed by the solar cell. A photon will then excite a negatively charged electron from the valence Band (low energy state) to the conduction Band (a higher energy state) leaving behind a positively charged vacancy, called a hole. For this energy transfer to create any usable energy, the photon must have an energy greater than the Band-gap of the material, or else the electron will immediately relax down and recombine with the hole and the energy will be lost as heat. Upon excitation above the bandgap the photon creates an electron and a hole which are now free to move throughout the semiconductor crystal. These act as charge carriers which transport the energy to the electrical contacts, which results in a measurable external current. These processes are shown in Figure 2.

The materials and structure of the solar cell are very important in this process. A solar cell is made out of semiconductor material which facilitates the creation and motion of charge carriers. The specific material determines the Band-gap and thus which wavelengths of light the cell can absorb, as well as many other optoelectronic properties

For more information on optoelectronic properties of materials, one may refer to virtually any relevant textbook on the subject. Several recommended texts include: Kasap, S. O. (2001). Optoelectronics and Photonics Principles and Practices. Upper Saddle River, New Jersey, Prentice-Hall Inc., Kasap, S. O. (2006). Principles of Electronic Materials and Devices. New York, McGraw-Hill., and Saleh, B. E. A. and M. C. Teich (2007). Fundamentals of Photonics. Hoboken, New Jersey, John Wiley Sons.

Once the electron-hole pair is created from incident sunlight, the solar cell must separate these charges or else they will quickly recombine and lose their energy. To do this, two layers of semiconductor are used: an n-type, which has an excess of fixed negative charges, and a p-type, which has an excess of fixed positive charges. When these two semiconductor layers are placed next to each other, opposing charge carriers self-annihilate in the region of the junction. The remaining fixed charges cannot move to recombine and thus create a built-in potential to the junction. This potential causes the charges to separate and move toward the contacts. If the electrons and holes survive long enough, then the solar cell can generate energy. This process can be seen in Figure 3, where light creates electron-hole pairs which are then carried towards the contacts due to the voltage difference between the n and p layers. Due to the opposite polarity of the different charge carriers, even though they travel in opposite directions, their currents add in the same direction.

The Band-gap presents a distinct trade-off in the performance of a material in a solar cell device. A wide Band-gap material does not absorb the energy of lower-energy photons. A small Band-gap material may absorb more solar energy; however, the photo-generated charge carriers lose much of this energy due to thermalization down to the Band-gap energy as the electrons travel out of the material. This is illustrated in Figure 4. Thus, regardless of the bandgap, a significant portion of solar energy is lost. As discussed in the following section, a nanowire array has the potential to resolve this issue, vastly increasing the maximum efficiency of the photovoltaic (Kempa, Naughton et al. 2009).

The ultimate figure of merit for solar cells is cost per watt; this decides whether a particular solar energy technology will become commercially viable. Our use of almost exclusive wet chemistry and abundant materials has the potential to be incredibly cheap and created on a massive scale. Solar energy has the potential to accommodate much of the world’s energy needs, but for it to actually become a major source of energy the materials used must be in sufficient supply. The materials we present are abundant enough to provide electricity for the entire world (Wadia, Alivisatos et al. 2009). This abundance, when combined with the inexpensive mass manufacturing possibilities of the wet chemistry process, indicates that this device could help achieve energy independence while safeguarding our environment.

Our design focuses on the use of cheap, abundant materials, as well as inexpensive fabrication methods in order to drive down the cost of producing solar cells. The use of a nanowire geometry should help to increase absorption, as well as decrease the carrier travel distance. Details of our design and the benefits therein will be discussed in the following sections.

2.2. How nanowires benefit solar cells

Nanostructures are constantly being found to improve the performance of objects and devices in many different fields, including photovoltaics. Specifically, nanowires are being used to enhance solar cells and have several key benefits including: decreased net reflectance (increased absorbance), increased junction area, and decreased carrier travel distance.

The increased surface area of a nanowire array and the inherent surface features result in decreased reflection and consequently higher absorption of incident light. (Hu and Chen 2007) This is largely due to light trapping and scattering effects where light gets reflected in between the nanowires, thus largely reducing the likelihood that it will be reflected outwards. This effect is shown in Figure 5 and is explained in more detail in reference (Muskens, Rivas et al. 2008). Reference (Cao, Fan et al. 2010) demonstrates resonant effects based on nanowire diameter and the weak angle dependence of incident light inherent in nanowires which contribute to increased absorption.

The nanowire core-shell geometry causes carriers to travel radially across the wire, thus reducing the distance the carrier must travel before it can reach the contact. The junction is also close to the contacts due to the nanowires, thus the separated carriers have a shorter distance to travel within the semiconductor and consequently a lower likelihood of recombining. Additionally this also means that the material quality can be lower than a traditional device (Tian, Zheng et al. 2007), an important factor with our material and growth procedures. We are examining the carrier transport mechanisms in these photovoltaic cells to see if the decreased carrier travel distance caused by the lateral movement reduces carrier extraction times. This may lead to increased energy extracted per photon, as hot carriers could be extracted before they lose their above-bandgap energy to thermalization.

The core-shell nanowire array allows for the use of ultrathin semiconductor layers, which reduce the amount of material used, while not sacrificing photon absorption. Although the materials used here are good absorbers already, Figure 6 demonstrates how the nanowires greatly improve light absorption. Since absorption is high while using ultrathin layers, the added benefit of reducing the amount of material used will lower overall costs of the design.

Yet another benefit to the core-shell geometry is that no matter where the photon is absorbed, it will be close to the junction. So if a photon travels halfway down a wire before being absorbed, or is absorbed at the tip of the wire, it has a similar likelihood of creating an electron-hole pair. In a bulk cell this is not the case as the further into a cell the photon travels, the further it is from the junction and the less likely it is that it will contribute to carrier generation.

Nanowires and their fabrication

Due to their geometry and scale, nanowires have generated massive research interest in the recent decades. Nanowires demonstrate exceptional surface to volume ratios, which increase inversely with the diameter of the nanowire. Carbon nanotubes have surface to volume ratios exceeding 10 6 cm 2 /cm 3. As such, nanowires have attracted much attention in the realms of catalytic science, energy storage, and electrochemistry; however, nanowire applications for energy generation are less forthcoming.

Many processes have been developed to fabricate nanowires. In general, ‘bottom-up’ methodologies are employed because ‘top-down’ techniques are limited in the achievable critical dimension and aspect ratios.

The technique of electrospinning forms nanofibers by taking advantage of the repulsive electrostatic forces present in a charged droplet of fluid. In the right conditions, a charged droplet can effuse a nanoscale stream that forms into a nanofiber. Composites may be used such that further processing can yield nanowires composed of metal or other materials (Shui and Li 2009).

Exceptionally high aspect ratio nanowires can also be grown along the step edges found in natural or manufactured structures. Zach et al. have demonstrated the ability to selectively electroplate at the atomic step edges of highly ordered pyrolytic graphite (Zach, Ng et al. 2000). Similarly, Menke et al. pioneered nanowire fabrication by electroplating along the undercut region of photoresist after wet etching an electrode masked by a lithographically-patterned photoresist film (Menke, Thompson et al. 2006).

Single-crystal semiconducting nanowires can be grown by the vapor-liquid-solid method (VLS growth). This popular method involves depositing a thin (1-10nm), often gold, seed layer on a substrate of the desired nanowire material. The substrate is then put into a vacuum chamber into which appropriate vapor-phase precursors for the material to be grown are introduced. The seed layer forms nucleation points that, at certain temperatures, facilitate the transfer of vapor species through the liquid phase to condensation on the substrate below the gold (Givargizov 1975).

Nanowires can also be fabricated by solution based processing. This is analogous to VLS growth except occurring in a solution rather than a vacuum chamber. In general, a catalyzing agent at the tip of the growing nanowire aids the transfer from ionic species in solution to solid species in the nanowire. Other components in solution inhibit growth on the substrate and sidewalls of the nanowire (Wang, Dong et al. 2006). Also of note is the similar polyol synthesis method (Sun, Mayers et al. 2003). This method involves the passivation of all but one crystal plane, allowing for the single dimensional growth along one crystal plane. High aspect ratio silver, gold, and palladium nanowires have been synthesized in this manner.

Standard lithography may also be used to create nanowires. However, the critical dimension (diameter) and aspect ratio are limited by the technology. The aspect ratios and dimensions achieved by the aforementioned techniques far outmatch those used in standard lithographic processes. However, the use of lithography does present two distinct advantages when dealing with electronic devices. For one, the nanowires can be easily integrated into other devices and structures that are fabricated by lithographic methods. For example, interconnects, transistors, and MEMS structures can be made together with nanowires. Secondly, for standard top-down fabrication methods, there exist many well-characterized means to make electrical connections with the outside world (wirebonding, solder bumping, etc). This is often an issue when working with bottom-up methodologies.

Finally, templated growth is a popular and versatile nanowire production method. This process is used in this work to fabricate core-shell nanowires. In this method, nanowires are masked by a template such as an anodized alumina membrane or a track etched polycarbonate membrane. Both of these membranes have extremely high aspect ratio pores. Anodized aluminum oxide (AAO) membranes have pores that range from nanometers to microns in diameter and up to hundreds of microns in length. To make nanowires, the desired material is filled into the template. A variety of methods have been used to achieve this including atomic layer deposition, centrifugation, electrophoretic deposition, and, most commonly, electrochemical deposition (ECD) (Cao and Liu 2008). In electrochemical growth a conductive seed layer is deposited on one side of the template, and the other side is introduced to a plating solution for the desired material. The final step in fabrication is the removal of the template, which is accomplished by dissolving the membrane in an appropriate solution (halogenated solvents for polycarbonate membranes or strong bases for AAOs).

3.1. Copper oxide. zinc oxide heterojunction nanowires:

The materials investigated here are copper (II) oxide and zinc oxide. These have bandgaps of 1.2 eV (Jiang, Herricks et al. 2002) and 3.3 eV (Ozgur, Alivov et al. 2005), respectively. There is a fair amount of copper (I) oxide present as well which has a Band-gap of 2.0 eV (Rakhshani 1986), but this material should decrease with optimization of our fabrication process. These materials were chosen for their ease of use in electrodeposition and their relative abundance. They have the added benefit of being natural n and p type materials. Undoped zinc oxide has a residual n-type conductivity (Look, Hemsky et al. 1999; Ozgur, Alivov et al. 2005), and CuO is naturally p-type. (Jiang, Herricks et al. 2002) Currently an indium tin oxide (ITO) thin film is used for the top contact, but future work will include investigating more economical alternatives.

The structure of the nanowire consists of co-axially stacked layers creating a core-shell arrangement as seen in Figure 7. The benefits of the structure have been discussed in section 2.2. The base and core of the nanowires consist of a copper core, which acts as the bottom contact, next is a shell of copper oxide around the copper core, and then a second shell of zinc oxide. Finally, a layer of indium tin oxide is deposited on the top. Due to the sputtering deposition, this top layer is not very conformal and covers mostly the top of the wires. This process can be replaced by an ALD deposition to achieve a conformal coating.

The Band diagram of the cell can be seen in Figure 8. This shows the Band-gaps of the materials and the voltage drop between them. This voltage drop is what pushes the electrons and holes away from each other to prevent them from immediately recombining. The Band-gap of ZnO is 3.3eV and as such can absorb only UV light out to 376nm. Cuprous oxide (Cu2O) can absorb light out to 620nm, and cupric oxide, CuO, can absorb radiation out to 1033nm. This encompasses the vast majority of the solar spectrum. The ZnO layer is very thin and has a wide Band-gap. Therefore its purpose is to act as the n-type material to create the built in voltage of the diode, which serves to extract charge carriers. The copper oxides serve as the absorber and p-type material in the diode.

The process of creating our nanowires will be discussed in section 3.3, however the latest iteration (before top contact deposition) can be seen in Figure 9.

3.2. Electrochemical and other fabrication methods for nanowire arrays

The geometric constraints when fabricating nanowires (especially core-shell structures) make the use of many common top-down techniques impractical. The dimensions of nanowires place constraints on fabrication with which many conventional deposition methods cannot comply. For example, physical vapor deposition (PVD) processes are line of sight methods, and, as such, these methods never yield impressive step coverage in high aspect ratio (length to width ratio) features such as nanowires (Madou 2002). Chemical vapor deposition performs better and is routinely used to coat or fill features with aspect ratios of five or ten (Gordon, Hausmann et al. 2003). However, this is still orders of magnitude removed from the typical nanowire aspect ratios. The following section details fabrication methods well-suited to the creation and alteration of nanowire arrays with special attention to copper and zinc oxides and core-shell structures.

Electrochemical deposition, shown in Figure 10, is the utilization of electrically driven redox reactions to solidify ions out of solution. Most often, metallic cations are reduced at a cathode, while oxidation at an anode of the same metal replaces the reduced ions. It is possible to plate alloys and compounds through careful manipulation of the plating bath. For example, many metal oxides, including copper and zinc oxides, can be deposited by careful control of the solution and electrical conditions (Golden, Shumsky et al. 1996)

One drawback of electro-deposition is its tendency towards non-conformal growth on non-planar surfaces. This is not an issue when growing nanowires through a template, which serves to constrain the growth. However, on rough or textured surfaces (such as a nanowire array), electrons gather in the asperities on the surface. deposition occurs at these points, which only exacerbates the issue as this make the surface rougher. Additives into the plating bath can alleviate this issue by gathering at the points of highest current density and inhibiting deposition, but this introduces impurities into the deposited material. The power of additives in creating conformal deposits is evidenced by the advent of copper interconnects in the integrated circuit industry where high-aspect ratio vias are filled by ECD (Andricacos 1999). However, aspect ratios are even more pronounced for the extreme geometries observed in nanowire arrays. There are also mass transfer concerns as the diffusion length for ions in solution exceeds the inter-nanowire spacing. Therefore, it is difficult (or improbable) for ions to travel the length of the nanowire to its base without being reduced and deposited prematurely. While ECD is difficult to implement for conformal coatings on nanowire arrays, it remains the method of choice to make high-quality nanowires through templated growth.

Electroless and immersion deposition are chemical methods to deposit metal films without applying an electric potential and have traditionally been used to conformally coat difficult geometries. Electroless plating (also known as autocatalytic deposition) utilizes reducing agents in solution to drive the reaction at the surface, which acts as a catalyst. Electroless deposition does not suffer from the current crowding effects of electrolytic deposition, but mass transfer effects can influence the deposition rates at different points in a nanowire geometry (Paunovic, Schlesinger et al. 1998).

Immersion plating is the displacement reaction of a more noble metal replacing a more active metal on a surface. For example, gold ions in solution would reduce and plate onto an iron bar. The iron surface would oxidize and dissolve into solution to maintain charge conservation. The reaction is self-limiting with deposits being only a few monolayers thick. Unlike autocatalytic and electrolytic plating, immersion deposits are exceptionally uniform regardless of surface topology. As such, immersion deposits are an attractive option for creating the ‘shell’ in nanowire core-shell applications. The main drawback is the material limitations: the depositing material must be higher in the galvanic series than the substrate (Langdon 1988).

The material constraints of immersion plating can be solved through a process known as contact plating. In this process, the substrate to be coated is put into electrical contact with a more electropositive (less noble) metal. Oxidation occurs at the electropositive metal, driven by the constituents of the bath. This oxidation yields electrons, which travel through the electrical contact and allow for reduction of ions out of solution. If the less noble metal is also the coating material, this reaction is self-limiting in that the reaction ceases when the work is coated. Thus, conformal coatings of less-noble metals may be electrochemically deposited on difficult geometries (Durney 1984).

While not electrochemical in nature, atomic layer deposition (ALD) should be mentioned as the ultimate method of conformal coating. Unlike the previous processes, ALD occurs from reactants in gas phase, generally at low pressures. In ALD a gas precursor is introduced and allowed to form a monolayer on the surface of a sample before being pumped out. Then, a second gas is introduced, which reacts with the monolayer to yield the desired film. This process is repeated to build up a film atomically, monolayer by monolayer. Because the monolayers are exceptionally uniform, conformal coatings on difficult topologies are easily achieved. Aspect ratios of almost 50 are easily coated uniformly (Ritala and Leskela 2001). The main drawback to ALD is the extremely low rate of deposition, which typically reaches a maximum at a few Angstroms per minute.

Finally, oxidation reactions are perhaps the most facile and effective way of creating exceptionally uniform and conformal layers on complex structures. Oxidation can be performed in either aqueous or gaseous environments. The latter case, generally referred to simply as thermal oxidation, has been well-characterized over a wide-range of temperatures (Cabrera and Mott 1949). Thin, uniform oxides can be formed on metals simply by applying heat in an oxygen atmosphere (Rusu, Gırtan et al. 2007; Njeh, Wieder et al. 2002). However, the high temperatures needed in thermal oxidation can have some undesired affects with regards to annealing, coefficients of thermal expansion, and diffusion. For example, a copper-zinc structure cannot be converted into a copper oxide – zinc oxide heterojunction by thermal oxidation because the materials will diffuse into one another. This forms brass, not a diode.

In the case of wet oxidation, the reaction can occur spontaneously (Tam and Robinson 1986) or can be driven electrically in a process known as anodization (Yamaguchi, Yamazaki et al. 1998). These processes have the advantage of taking place at low temperatures. Anodization can be viewed as the reverse process as electroplating. In anodization, a positive potential applied to the piece will cause oxygen ions in solution to oxidize (in the electrochemical sense) atoms at the surface. Whereas, in ECD, the oxidized ions at the anode dissolve into solution, in anodization, the oxides remain at the anode and build up a conformal film. Incidentally, it is by this process that the AAO templates are made for the initial nanowire growth in the process presented in this paper.

3.3. Fabrication

Our fabrication takes place at the Tufts Micro and Nano Fabrication Facility (TMNF) at Tufts University, with some work being done at the Center for Nanoscale Systems (CNS) at Harvard University. TMNF is a class 1000 cleanroon where most of our wet chemical and sputtering processes are performed. CNS is a large 10,000 sq. ft. class 1000 cleanroom where most of our imaging is done. We also perform our atomic layer deposition at CNS as well.

Our fabrication flow process can be seen in Figure 11. This diagram shows the process from start to finish and includes the creation of the copper nanowires, oxidation of the copper oxide layer, deposition of the ZnO layer, and finally the deposition of the top contact layer. The process starts by obtaining an anodized aluminum oxide template which can either be purchased commercially or created by anodizing an aluminum film. Copper is then sputtered on one side of the template become the electrode and act as a seed layer for the nanowires. The AAO then acts as a mask for the through-plating of copper. Five to ten microns of copper is electroplated into the pores. The AAO is then dissolved in a 10% solution of potassium hydroxide (KOH) for 20 minutes, revealing a densely packed copper nanowire array (as shown in Figure 9 above).

The electrochemical deposition (ECD) of copper is performed using a solution of 0.75 M copper sulfate (CuSO4) and 1.5 M sulfuric acid (H2SO4) at room temperature with air agitation. This reaction is current limited with the supplied current at less than or equal to 5mA/cm². The zinc oxide ECD is performed using a solution of 0.1 M zinc nitrate (ZnNO3) at 70. 80 C at a potential of 0.75 volts.

Future research

Nanowires and especially nanowire solar cells are still in an early stage of development and are found almost exclusively in the laboratory, although there are several companies planning products which utilize nanowires, i.e. Bandgap Engineering, QDSoleil, Illuminex. As with so many new technologies, there is much work yet to be done and there are still many improvements, optimizations, and options to be explored in the research presented here. Several areas which require further research and investigation are with conformal coatings of the nanowires and general process optimization, difference material choices, and long-term stability.

One of the biggest difficulties in growing these core-shell nanowires is achieving conformal coatings to create the core-shell structure. Electrochemical methods, besides being cheap, have proven to be much better than physical vapor deposition techniques, however due to the extremely small distances between the nanowires, often only the upper portions of the nanowires are coated. Several of the ways we are trying to mitigate this problem is by testing to see how atomic layer deposition compares to the ECD process. Also, contact plating shows promise in conformal, electrochemical coating of nanowire geometries. Much of the fabrication process already developed needs further optimization. Several factors which require tweaking are the specific parameters to obtain optimal widths and lengths of the nanowires, specific temperature and duration of thermal oxidation, specific voltage and concentration of the electrochemical baths, and especially our top contact deposition. We currently sputter coat an indium tin oxide transparent conductor, however this is an expensive material and a very non-conformal deposition. Sol-gel deposition techniques and alternate transparent conduction oxides such as doped ZnO should be investigated.

The oxides currently used were chosen specifically for their ease of use with ECD as well as their abundance in the earth’s crust. This allowed us to make quick initial progress inexpensively, as well as to follow our goal of creating a low-cost solar alternative. However the copper and zinc oxides are not particularly well suited to the solar spectrum as they have relatively wide Band-gaps and it would behoove us to look into other material choices. The fact that copper forms a Schottky barrier with copper oxide precludes the creation of an optimal ohmic contact reducing the efficiencies we may obtain, and as such a different bottom contact material or absorber material should be investigated. Another option is to optimize this process for a Schottky barrier PV cell, where the junction is formed not from a difference in doping but from the depletion layer induced by the metal at the metal-semiconductor junction.

One potential problem to be wary of is that the nanowires are extremely pressure sensitive. Locations on the cell where they have been handled are visibly damaged under a microscope, and in some cases visible to the eye. Although unavoidable in the early stages of research, this is an important problem which must be addressed down the line. Work must be done to provide adequate handling techniques during the fabrication process, as well as sufficient encapsulation to ensure long-term operation when deployed.

Conclusion

In this chapter, we have presented a novel fabrication process for the creation of oxide based core-shell nanowire photovoltaic cells. The major FOCUS of this design process has been to keep costs low. To do this, earth-abundant materials have been investigated as well as wet chemical fabrication methods. As it is early in the design, our samples are plagued by issues which should be rectified by optimization of the fabrication process. Although we have seen a diode response from the fabricated samples, we are unsure of whether this is due to the possible schottky diode formed between the copper and copper oxide layers, or from the pn junction. These devices have the potential to become incredibly cheap solar cells but to achieve this goal further research and development is necessary and warranted.

Acknowledgments

The authors would like to sincerely thank the Tufts Micro and Nanofabrication facility as well as Harvard CNS for use of their clean room facilities. We would like to thank the Wittich Energy Sustainability Research Initiation Fund for their funding as well as the National Science Foundation as this material is based upon work supported under a National Science Foundation Graduate Research Fellowship.

How to Make a Solar Panel (Copper Sheet Method)

This article was co-authored by Meredith Juncker, PhD. Meredith Juncker is a PhD candidate in Biochemistry and Molecular Biology at Louisiana State University Health Sciences Center. Her studies are focused on proteins and neurodegenerative diseases.

wikiHow marks an article as reader-approved once it receives enough positive feedback. In this case, several readers have written to tell us that this article was helpful to them, earning it our reader-approved status.

This article has been viewed 140,148 times.

Homemade solar panels/cells make a great DIY project for adults and kids alike. One simple way to make a cheap solar panel is by using cuprous oxide, an oxidized form of copper. While this is a great experiment to show how a solar panel works, keep in mind that it will not produce much power at all.

Making Cuprous Oxide

Cut 2 copper sheets. You can use sheet metal shears to do this easily. Make the sheets the same size. You want 1 sheet to fit on your burner or hot plate, and both to fit in the 2-liter bottle. Making them both 6 in (15 cm) squares should work well. [1] X Research source

Clean your copper sheets. Use a degreaser to remove any oils or grease from your copper sheet. You do not want them to react with the copper or to prevent oxidation from happening. You should also wear gloves to avoid getting oil from your skin on the copper. Also be sure to scrub the copper with steel wool or sandpaper to remove any corrosion. [2] X Research source

Place 1 copper sheet on a hot plate. Once you have placed a sheet on the hot plate, turn the hot plate on. This will heat the copper and provide the energy needed for the copper to react quickly with the oxygen in the air. This speeds up the natural oxidation process considerably. [3] X Research source

Cooking the extra 30 minutes makes the cuprous oxide layer thick and brittle. This allows it to break away from the copper. A thin layer of cuprous oxide would remain on the copper, covering up the cupric oxide layer that needs to be exposed. [5] X Research source
Note that cupric oxide (Copper (II) oxide) is the fully oxidized form, and cuprous oxide (Cu2O) is still in an active state.
You can rinse the sheet under water to remove the remaining black deposits.
Cupric oxide is a semiconductor and must be exposed in order to make the solar cell function.

Assembling the Solar Cell

Place the 2 copper sheets into your container. You will need to bend both pieces to match the curvature of the plastic bottle. Both pieces need to be able to fit in the bottle without touching each other. Be sure not to damage the red cuprous oxide layer when bending the cooked sheet. [7] X Research source

Connect alligator clips to each sheet. Use the alligator clips to attach both pieces to opposite sides of the plastic bottle. The copper sheet with red cuprous oxide should be connected to the clip that will lead to a negative terminal, and the clean copper sheet could be joined to a clip leading to a positive terminal. [8] X Research source

For example, dissolve 1 ⁄4 cup (59 mL) of salt into 3 ⁄4 cup (180 mL) of water.
Using distilled or deionized water will reduce the risk of contaminants.

Add saltwater to cover most of the 2 plates. Leave about 2 inches (5.1 cm) of space above the saltwater.This will allow current to travel from the negative terminal to the positive terminal. Be careful to keep the clips at the top of the two sheets dry. Otherwise, the water on the clips might interfere with your readings. [9] X Research source

Testing Your Solar Cell

Place the solar cell in the sun. When the sun hits the cuprous oxide layer, it causes electrons to be released. The cuprous oxide is not conductive, but the electrons are able to move through the salt water to the conductive copper plate. This plate transfers the electrons to the wires. [10] X Research source

Hook the alligator clips to a multimeter. Plug the other end of your alligator clips into a multimeter or ammeter. Be sure that your meter can function in the microamp (0.000001 amps) range. Plug the positive alligator clip into the positive terminal of your meter and the negative alligator clip into the negative terminal of your meter. [11] X Research source

Set your meter to read microamps. A very small amount of current will be flowing. This current should fall somewhere between 0 and 50 microamps. Turning the cell so that the cuprous oxide layer is facing the most direct sunlight will give you the most current. [12] X Research source

Expert QA

Meredith Juncker is a PhD candidate in Biochemistry and Molecular Biology at Louisiana State University Health Sciences Center. Her studies are focused on proteins and neurodegenerative diseases.

Copper turns a bluish-green color (called patina) when in salt water. This is due to saltwater corrosion.

Thanks! We’re glad this was helpful. Thank you for your feedback. As a small thank you, we’d like to offer you a 30 gift card (valid at GoNift.com). Use it to try out great new products and services nationwide without paying full price—wine, food delivery, clothing and more. Enjoy! Claim Your Gift If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even 1 helps us in our mission. Support wikiHow

If I have copper sheets that have already been oxidized from making previous solar cells, is there a way to re-oxidize the copper sheets in order for them to be re-cooked and undergo the same process?

Meredith Juncker is a PhD candidate in Biochemistry and Molecular Biology at Louisiana State University Health Sciences Center. Her studies are focused on proteins and neurodegenerative diseases.

Copper sheets previously used in solar cells can be melted down and stripped of impurities, to form high-grade copper as a product, but this would require lab equipment.

Unfortunately this method is not efficient for powering much of anything, even something small. It is best used to show the chemistry involved in making solar panels, rather than as a viable solar panel.

You can do this without saltwater if you put a conductive metal mesh or copper border over the cuprous oxide layer to transport electrons from the surface to the wire. These methods make the panel flat, but are less efficient because the mesh blocks some sunlight and only electrons near the conductor can be transported. [13] X Research source [14] X Research source

Do not try to remove all of the black cuprous oxide. This might result in damage to the cupric oxide layer.

Don’t expect to run your house off this. It would require acres of land and millions of dollars of copper just to produce enough power to run the electric stove used in step two. While this shows the same scientific principles involved in commercially viable photovoltaic cells, it’s orders of magnitude less efficient.

How to Quickly Turn Copper Darker

11 Ways to Boost Your Solar Efficiency

How to Keep Your Solar Panels Safe From Hail: Informational Guide

How to Pick the Best Solar Panels Everything You Should Look For

Sources:

https://patents.google.com/patent/US20140060639A1/en
https://atlasofscience.org/copper-oxide-for-low-cost-and-stable-perovskite-solar-cells/
https://www.intechopen.com/chapters/16350
https://www.wikihow.com/Make-a-Solar-Panel-(Copper-Sheet-Method)

US20140060639A1 ( en )	2014-03-06	Copper oxide core/shell nanocrystals for use in photovoltaic cells
Ajayan et al.	2020	A review of photovoltaic performance of organic/inorganic solar cells for future renewable and sustainable energy technologies
Haider et al.	2018	A comprehensive device modelling of perovskite solar cell with inorganic copper iodide as hole transport material
Sun et al.	2019	Piezo-phototronic effect enhanced efficient flexible perovskite solar cells
Zhang et al.	2014	Structure engineering of hole–conductor free perovskite-based solar cells with low-temperature-processed commercial carbon paste as cathode
Xu et al.	2014	Surface engineering of ZnO nanostructures for semiconductor‐sensitized solar cells
Sun et al.	2017	Three-dimensional nanostructured electrodes for efficient quantum-dot-sensitized solar cells
Fan et al.	2009	Challenges and prospects of nanopillar-based solar cells
AU2019257470A1 ( en )	2019-11-21	A Photovoltaic Device
Cardoso et al.	2012	Fabrication of coaxial TiO 2/Sb 2 S 3 nanowire hybrids for efficient nanostructured organic–inorganic thin film photovoltaics
Lee et al.	2011	Solid-state dye-sensitized solar cells based on ZnO nanoparticle and nanorod array hybrid photoanodes
EP1176646A1 ( en )	2002-01-30	Solid state heterojunction and solid state sensitized photovoltaic cell
Hong et al.	2019	Improved efficiency of perovskite solar cells using a nitrogen-doped graphene-oxide-treated tin oxide layer
Feng et al.	2015	Three-dimensional hyperbranched TiO 2/ZnO heterostructured arrays for efficient quantum dot-sensitized solar cells
TWI540743B ( en )	2016-07-01	Semiconductor film-forming coating liquid, semiconductor film, semiconductor element and manufacturing method thereof
TW200810136A ( en )	2008-02-16	Photovoltaic device with nanostructured layers
Desai et al.	2012	Solid-state dye-sensitized solar cells based on ordered ZnO nanowire arrays
Ren et al.	2018	Strategies for high performance perovskite/crystalline silicon four-terminal tandem solar cells
Vildanova et al.	2017	Niobium-doped titanium dioxide nanoparticles for electron transport layers in perovskite solar cells
CN112018209A ( en )	2020-12-01	Perovskite-silicon heterojunction laminated solar cell and manufacturing method thereof
Ubani et al.	2017	Moving into the domain of perovskite sensitized solar cell
Ranjitha et al.	2019	Effect of doped TiO2 film as electron transport layer for inverted organic solar cell
Wu et al.	2021	Progress in blade-coating method for perovskite solar cells toward commercialization
Mashreghi et al.	2018	Improving perovskite/carbon interfacial contact in carbon based perovskite solar cells by changing two-step spin coating sequence
Wang et al.	2018	In situ growth of PbS nanocubes as highly catalytic counter electrodes for quantum dot sensitized solar cells

Copper oxide solar cell. Copper oxide solar cell

US20140060639A1. Copper oxide core/shell nanocrystals for use in photovoltaic cells. Google Patents

Links

Images

Classifications

Abstract

Description

Claims ( 15 )

Priority Applications (2)

Applications Claiming Priority (2)

Family Applications (1)

Cited By (10)

Families Citing this family (1)

Citations (3)

Patent Citations (4)

Cited By (16)

Similar Documents

Legal Events

Copper oxide solar cell

Related Articles:

Leave a Reply Cancel reply

Electrodeposited Copper Oxide and Zinc Oxide Core-Shell Nanowire Photovoltaic Cells

The case for solar

2.1. Solar cell basics

2.2. How nanowires benefit solar cells

Nanowires and their fabrication

3.1. Copper oxide. zinc oxide heterojunction nanowires:

3.2. Electrochemical and other fabrication methods for nanowire arrays

3.3. Fabrication

Future research

Conclusion

Acknowledgments

How to Make a Solar Panel (Copper Sheet Method)

Making Cuprous Oxide

Assembling the Solar Cell

Testing Your Solar Cell

Expert QA

You Might Also Like

Leave a Reply Cancel reply