SOLID-STATE SOLAR PAINT

Abstract

Methods and devices for forming painted circuits using multiple layers of electrically conductive paint. In one aspect, a painted circuit includes a substrate and one or more paint layers applied to the substrate where the one or more paint layers each form an electrical component of the painted circuit, and where the one or more paint layers includes a p-type hole conducting paint layer applied to the substrate, a photosensitized paint layer applied to the p-type hole conducing paint layer, an n-type electron conducting paint layer applied to the photosensitized paint layer, and a transparent protective paint layer applied to the n-type electron conducting paint layer.

Description

BACKGROUND

Traditional solar cells use substrates with highly regular crystalline structure, for example, crystalline silicon. Newer technologies include thin-film, amorphous solar cells to create discrete layers of individual material with highly regular and predictable chemical structure. Commercial solar cell fabrication, in general, requires highly specialized equipment, which restricts fabricated solar cells to geographic locations with access to the complex manufacturing equipment and/or specialized shipping and installation capabilities.

SUMMARY

This specification relates to paint circuits that can be formed using multiple layers of electrically conductive paint, and can, for example, be used to form a solar paint circuit to convert sunlight into electricity.

In general, one innovative aspect of the subject matter described in this specification can be embodied in a painted circuit including a substrate and one or more paint layers applied to the substrate where the one or more paint layers each form an electrical component of the painted circuit. The one or more paint layers of the painted circuits includes a p-type hole conducting paint layer applied to the substrate, a photosensitized paint layer applied to the p-type hole conducing paint layer, an n-type electron conducting paint layer applied to the photosensitized paint layer, and a transparent protective paint layer applied to the n-type electron conducting paint layer. A paint layer of the one or more paint layers includes a conductive paint formulation having a resistance that is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and a thickness of the given paint layer, and where the resistance of the conductive paint formulation including a conductive material having a higher resistivity provides a higher resistance than the resistance of the conductive paint formulation including a conductive material with a lower resistivity.

These and other embodiments can each optionally include one or more of the following features. In some implementations, the p-type hole conducting paint layer includes p-type nanoparticles (e.g., copper oxide nanoparticles).

In some implementations, the photosensitized paint layer includes a semiconductor paint layer (e.g., titanium dioxide nanoparticles) and a photosensitized dye paint layer (e.g., copper phthalocyanine).

In some implementations, the n-type electron conducting paint layer includes n-type nanoparticles (e.g., aluminum-doped zinc oxide nanoparticles).

In some implementations, the painted circuit includes two or more contacts, where each contact includes a metallic foil affixed to a substrate or an n-type electron conducting paint layer and in electrical contact with the substrate or the n-type electron conducting paint layer, respectively.

In general, another aspect of the subject matter described in this specification can be embodied in methods that include a process for manufacturing a painted circuit including providing a substrate and applying one or more paint layers on a surface of the substrate, where the one or more paint layers each forms an electrical component of the painted circuit. Applying the one or more paint layers includes applying a p-type hole conducting paint layer to the substrate to yield a layer of the p-type hole conducting paint in direct contact with the substrate, applying a photosensitized paint to the p-type hole conducting paint layer to yield a layer of the photosensitized paint in direct contact with the p-type hole conducting layer, applying an n-type electron conducting paint to the photosensitized paint layer to yield a layer of the n-type electron conducting paint in direct contact with the photosensitized paint layer, and applying a transparent protective paint to the n-type electron conducting paint layer to yield a layer of the transparent protective paint in direct contact with the n-type electron conducting paint layer, where a first paint layer of the one or more paint layers includes a conductive paint formulation having a resistance that is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and a thickness of the given paint layer, and where the resistance of the conductive paint formulation including a conductive material having a higher resistivity provides a higher resistance than the resistance of the conductive paint formulation including a conductive material with a lower resistivity.

In some implementations, applying a p-type hole conducting paint includes applying a layer of p-type nanoparticles (e.g., copper oxide nanoparticles) dispersed in solution (e.g., deionized water and a surfactant) on to the substrate and sintering (e.g., photonic sintering) the p-type nanoparticles to form an electrically continuous p-type hole conducting paint layer.

In some implementations, applying a photosensitized paint includes applying a layer of semiconductor paint including semiconductor nanoparticles (e.g., titanium dioxide nanoparticles) dispersed in solution (e.g., deionized water and surfactant) on the p-type hole conducting paint layer and sintering (e.g., photonic sintering) the semiconductor nanoparticles to form an electrically continuous semiconductor paint layer. A layer of photosensitized dye paint (e.g., copper phthalocyanine dispersed in a denatured alcohol) is applied to the semiconductor paint layer and thermally processed (e.g., photonic curing) to chemisorb the photosensitized dye paint layer onto the semiconductor paint layer.

In some implementations, applying an n-type electron conducting paint includes applying a layer of n-type nanoparticles (e.g., aluminum-doped zinc oxide nanoparticles) dispersed in solution (e.g., deionized water and surfactant) on the photosensitized paint layer and sintering (e.g., photonic sintering) the n-type nanoparticles to form an electrically continuous n-type electron conducting paint layer.

In some implementations, the painted circuit is thermally processed (e.g., by photonic curing). The thermal processing of the painted circuit may be done after all of the paint layers are applied to the painted circuit. In some implementations, the thermal processing is done prior to applying a transparent protective coating to the painted circuit (e.g., applying the transparent protective coating to the n-type electron conducting paint layer). Thermal processing of the painted circuit may be done after applying the transparent protective coating to the painted circuit.

Particular embodiments of the subject matter described in this specification can be implemented to realize one or more of the following advantages. Unlike traditional commercial solar cell fabrication, solar paint circuits can be fabricated with few tools (e.g., a hand mixer and an aerosolized sprayer) by individuals in any location (e.g., even in remote regions that do not have access to electricity or other resources required by conventional approaches). The solar paint circuits discussed herein are created using combinations of basic, inexpensive materials to form electronic circuits, which reduces fabrication complexity and reduces the cost to the manufacturer and end-user. In general, many of the materials used in the solar paint circuits are less hazardous and are less expensive to manufacture and ship than materials used in traditional solar cells. The paint circuits described here have a reduced upfront capital expenditure requirement relative to traditional circuit fabrication and can be fabricated on-site as result, reducing import/export tax or customs duty in countries where traditional circuit fabrication facilities cannot be established. Additionally, existing infrastructure in commonly found paint factories can be converted easily to produce solar paint circuits, whereas traditional solar cell fabrication requires highly specialized equipment. The relationship between the electrically active material and its paint substrate enable the electrical properties of the paint to be selected using relatively simple mathematical analyses. Additionally, the ability to control the viscosity of the paint and/or the number of layers applied enables the electrical characteristics to be easily changed by changing the viscosity and/or the number of layers of paint applied. This type of flexibility is typically unavailable with more conventional, high-precision circuit fabrication methods.

The details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example solar paint circuit.

FIG. 2 is a flow chart of an example process for producing solar paint.

FIG. 3 is a flow chart of another example process for producing solar paint.

FIG. 4 is a flow chart of another example process for producing solar paint.

FIG. 5 is a flow chart of an example process for painting a solar paint circuit.

FIG. 6 is a flow chart of another example process for painting a solar paint circuit.

FIG. 7 is a flow chart of an example process for painting a p-type hole conducting paint layer.

FIG. 8 is a flow chart of an example process for painting a photosensitized paint layer.

FIG. 9 is a flow chart of an example process for painting an n-type electron conducting paint layer.

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

Overview

Described below are devices, systems, and methods for producing solar paint and solar paint circuits. A paint circuit (e.g., a solar paint circuit) is created through a layer-by-layer application of electrically conductive paint (e.g., solar paint) to a surface of a substrate. The substrate can be, for example, a piece of wood, brick, plaster, stone, metal surface, or another surface to which paint can be applied. The application of layers of solar paint to the substrate can be done by hand using an aerosol dispenser or other aerosolized spray tool.

Though the term “solar paint circuit,” and “solar paint” are used in the context of describing particular embodiments of the subject matter, it is not meant to be limiting. Other paint circuits can be implemented which do not integrate solar energy (e.g., a battery, a light-emitting diode, an antenna, or other circuit elements), as well as paint layers that are not directly involved in forming solar-integrating circuits.

In some implementations, a painted circuit can be created by applying a single paint layer to a substrate. For example, a simple resistive circuit can be created by applying a single paint layer to the substrate. As discussed in more detail below, the paint layer applied to the substrate can be a conductive paint formulation having a resistance that is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and thickness of the paint layer. In some implementations, when conductive material with higher resistivity is included in the paint formulation, the resistance of the paint formulation will be higher than when conductive material with lower resistivity is included in the paint formulation.

In some implementations, a paint layer is applied through a template (e.g., a mask, stencil, and/or screen printing tool), such that paint is applied to a substrate in a portion of the template but is prevented from being applied to the substrate in a second, different portion of the template.

In some implementations, a paint layer can be applied using a paint brush, paint roller, or other painting tool. Paint for a paint layer can be aerosolized and applied to a substrate using an aerosol spray tool, spray can, or other aerosol dispensers.

In some implementations, multiple paint layers are applied to the substrate to create a painted circuit. For example, after a first layer of paint is applied to the portion of the substrate, other layers can be applied to other portions of the substrate (e.g., adjacent to the first layer) and/or applied to already painted portions of the substrate (e.g., applied over the first layer of paint). Each layer of paint forms an electrical component of the painted circuit (e.g., an electron transport layer, a hole transport layer, etc.).

A paint layer can include a conductive paint formulation where a resistance of the paint layer is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and a thickness of the given paint layer, and where the resistance of the conductive paint formulation including a conductive material having a higher resistivity provides a higher resistance than the resistance of the conductive paint formulation including a conductive material with a lower resistivity.

Adjusting a viscosity of the paint layer can change a thickness of the paint layer applied to the substrate, which in turn will affect the resistance of the paint layer. For example, a paint formulation with a higher viscosity will result in a thicker paint layer than a paint formulation with a lower viscosity, and thicker layers of paint will generally have higher resistance in a direction perpendicular to the plane of the layer than thinner layers of similar formulation.

In some implementations, a droplet size of a paint dispersed by an aerosolized sprayer determines, in part, a thickness of the paint layer applied to the substrate, which in turn will affect the resistance/conductance of the paint layer. For example, a larger droplet size of a paint dispensed by an aerosolized sprayer will result in a thicker paint layer than a smaller droplet size of the same paint dispensed by the aerosolized sprayer, and thicker layers of paint will generally have higher resistance in a direction perpendicular to the plane of the layer than thinner layers of similar formulation.

In some implementations, one or more paint layers can be sintered to yield structural and/or electrical properties of the one or more paint layers. Sintering of paint layers which include one or more nanomaterials (e.g., nanoparticles) can, for example, cause densification of the paint layers by agglomeration, reduction of porosity, and/or grain growth. Sintering of paint layers can be performed using, for example, a furnace, a rapid thermal processing system, a high-powered lamp (e.g., photonic sintering), or other system that provides elevated temperatures for a duration of a sintering process.

Various types of circuits and devices can be fabricated using solar paint including a solar cell described below. Other solar paint circuits can be created using the techniques described below, including a solar battery, where a solar cell charges a battery. Another example of a solar paint circuit is a solar-powered streetlight, including a solar cell, a battery, and a light-emitting circuit. Another example of a solar paint circuit is a solar cell including an output regulator to regulate the solar cell to a maximum power point of the solar cell, which can be used as part of a cell phone charging circuit. Various circuit elements, such as resistors, capacitors, diodes, and transistors, can be fabricated using the solar paint described herein.

Though the example circuit described below is depicted in block diagram form as single layers of each respective paint layer, multiple applications (e.g., multiple layers) of particular paint layers can be used to achieve desirable electrical and/or functional properties. Additionally, though the example depicted below describes a single sub-circuit (e.g., a single solar cell) integrated and/or painted on one paint circuit, multiple sub-circuits may be incorporated and/or painted to form a larger paint circuit (e.g., multiple solar cells) to achieve desired device performance).

Example Solar Paint Circuit

FIG. 1 is a block diagram of an example solar paint circuit 100. The solar paint circuit 100 includes a substrate 102, a p-type hole conducting paint layer 104, a photosensitized paint layer 106, an n-type electron conducting paint layer 108, and a transparent protective paint layer 110. In some implementations, the solar paint circuit 100 is a solar cell. A solar cell is an electrical device that converts the energy of light (e.g., sunlight) into electricity. Photons (e.g., sunlight) are absorbed in the photosensitized paint layer 106, and charge generation of electrons and holes occurs. The generated charges are then separated and the electrons move towards the cathode and holes move towards the anode, respectively, to generate electricity.

The p-type hole conducting paint layer 104 can be created by applying a p-type hole conducting paint to at least a portion of the substrate 102 (e.g., a surface composed of wood, metal, plaster, stone, brick, or another paintable material). In some implementations, the p-type hole conducting paint layer 104 forms an anode for the solar paint circuit 100. The p-type hole conducting paint layer 104 can be formed by an aqueous paint composition including p-type nanomaterials dispersed in a solution. Formulations for the p-type hole conducting paint layer 104 are discussed in further detail below.

The photosensitized paint layer 106 forms a layer where photons can be absorbed and charge generation takes place in the solar paint circuit 100. The photosensitized paint layer 106 can be formed from paint compositions including an electron acceptor, a dye, and a solution. The photosensitized paint layer 106 is depicted as a single functional layer in solar paint circuit 100, however, it can be created by applying two or more different paint layers including a semiconductor paint layer having an electron acceptor material and a photosensitized dye paint layer. Formulations for the photosensitized paint layer 106 including formulations for a semiconductor paint layer and a photosensitized dye paint layer are discussed in further detail below.

The n-type electron conducting paint layer 108 is applied to the photosensitized paint layer 106. In some implementations, the n-type electron conducting paint layer 108 forms a cathode for solar paint circuit 100. The n-type electron conducting paint layer 108 can be formed by an aqueous paint composition including n-type nanomaterials dispersed in a solution. The n-type electron conducting paint layer 108 can be transparent or semi-transparent to allow light to reach the photosensitized paint layer 106 below. In some implementations, rather than an n-type electron conducting paint layer 108, an electrically conductive mesh (e.g., a wire mesh) is used as a cathode layer for solar paint circuit 100.

A transparent protective paint layer 110 is applied to the n-type electron conducting layer 108. The transparent protective paint layer 110 can be a transparent protecting coating and can be electrically insulating (e.g., laminate, polyurethane finish, shellac). In some implementations, the transparent protective paint layer 110 encapsulates a portion or all of the exposed surfaces of the solar paint circuit 100. The transparent protective paint layer 110 forms a protective layer over part or all of the solar paint circuit 100 to protect the solar paint circuit 100 paint layers from environmental effects (e.g., UV radiation, weather, water/humidity). In some implementations, the transparent protective paint layer 110 is semi-transparent, and/or only transparent to certain wavelengths ranges (e.g., transparent to visible wavelengths). In some implementations, the transparent protective paint layer 110 is omitted, depending in part on application and/or environmental factors (e.g., level of exposure to weather). When the transparent protective paint layer 110 is omitted, the n-type electron conducting paint layer 108 can function as a conductive protective layer (e.g., indium tin oxide).

The solar paint circuit 100 operates to absorb photons from the ambient environment (e.g., solar rays) in the photosensitized paint layer 106, such that electron-hole pairs are formed within the photosensitized paint layer 106, and charge separation occurs between the p-type hole conducting paint layer 104 and the n-type electron conducting paint layer 108.

In some implementations, the separated charges from solar paint circuit 100 are then used to charge (e.g., trickle charge) a battery. The solar paint circuit 100 can be combined with other circuit elements to produce a solar-powered light (e.g., a solar-powered streetlight). For example, the solar paint circuit 100 may be combined with a solar battery and a light-emitting circuit, where the solar paint circuit 100 can be used to generate electricity from sunlight to charge (e.g., trickle charge) a solar battery, which can then be used to power a light-emitting circuit. The powered light-emitting circuit can then emit light in a particular range of wavelengths (e.g., visible light).

In some implementations, multiple solar paint circuits 100 are connected together in series. Connecting multiple solar paint circuits 100 together in series can increase the amount of electricity generated and available to power another circuit (e.g., a light-emitting circuit, a cell phone device, etc.) or charge a solar battery.

In some implementations, multiple solar paint circuits are electrically connected together to form larger systems of circuits. The multiple solar paint circuits can be of a same or of different types, and can be connected together in series and/or in parallel, depending on functionality of the larger system. For example, multiple solar cells can be connected in series to one or more solar batteries such that multiple solar cells can be used to charge a solar battery, increasing throughput.

In some implementations, electrical contacts 112 can be included in the solar paint circuit 100. The electrical contacts can include a first contact (e.g., metallic foil, metallic mesh, cold weld bonding compound, solder ball, alligator clip, or the like) affixed to an n-type electron conducting paint layer 108 or to a substrate 102. A second contact (e.g., metallic foil, metallic mesh, cold weld bonding compound, solder ball, alligator clip, or the like) can be affixed to a p-type hole conducting paint layer 104. The electrical contacts can be used to connect to the solar paint circuit 100 to an external device (e.g., a mobile phone, computer, or other battery-operated device). The electrical contacts 112 can also be used to connect the solar paint circuit 100 to other solar circuits, for example, to daisy-chain a set of solar cell painted circuits, to increase throughput for powering and/or charging a user device (e.g., a cell phone or computer), or charging a solar battery.

Example Process for Producing Solar Paint Formulations

Solar paint circuits, including the solar paint circuit 100 described herein with reference to FIG. 1, include multiple layers of solar paint. Solar paint can include various formulations selected to give the solar paint layers applied with the particular solar paint different electrical (e.g., resistive/conductive), reactive (e.g., photo-reactive), dielectric (e.g., voltage breakdown) and physical properties (e.g., viscosity). In some implementations, paint formulations are aqueous and include water, a solvent (e.g., ethanol), and/or an emulsifier.

In some implementations, paint formulations include nanoparticles (e.g., metallic or semiconductor nanoparticles) dispersed in a solution (e.g., ethanol, deionized water and surfactant).

Implementations of solar paints include conductive paint (e.g., for n-type electron conducting and p-type hole conducting paint layers). Conductive paint can be an aqueous composition including one or more conductive or semiconductor nanomaterials (e.g., metallic or semiconductor nanoparticles) dispersed in solution. Examples of suitable nanomaterials include aluminum-doped zinc oxide nanoparticles, copper oxide nanoparticles, and carbon-based nanomaterials (e.g., carbon nanotubes). Examples of suitable solution include deionized water with a dispersant (e.g., benzenesulfonic acid or sodium dodecyl sulfate) and denatured alcohol (e.g., denatured ethanol). In some implementations, conductive nanomaterials (e.g., nanoparticles) are selected based in part on a transparency of the resulting conductive paint including the conductive nanomaterials. Additionally, deflocculants (e.g., sodium lauryl dodecasulfide or a basic salt like sodium carbonate or potassium carbonate) can be added to the conductive paint including the conducting nanomaterials to prevent flocculation, minimize surface energy of the dispersed nanoparticles, and assist in dispersion of the nanomaterials and improve transparency.

In some implementations, the conductive paint is treated in an ultrasonic bath to break up aggregated nanomaterials and filtered (e.g., through a microfiber cloth) in order to fully disperse the nanomaterials in the conductive paint. In some implementations, the conductive paint may be dispersed using a ball mill treatment and/or high-shear mixing.

FIG. 2 is a flow chart of an example process for producing solar paint. Referring to FIG. 2, conductive paint can be prepared by process 200. In 202, a suitable conductive material is dispersed in solution to yield the conductive paint. For example, a conductive material (e.g., aluminum-doped zinc oxide nanoparticles) may be dispersed in solvent (e.g., ethanol) to yield a conductive paint. In 204, the conductive paint can optionally be agitated (e.g., in an ultrasonic bath or stirred) and filtered (e.g., through a microfiber cloth) to evenly disperse the nanomaterial in the solution.

Conductive paints prepared according to the process of FIG. 2 can include n-type semiconductor materials as the conductive material, e.g., for use as an n-type electron conducting paint layer 108. Examples of n-type semiconductor materials include carbon-based materials, such as graphite powder, activated charcoal, and n-type carbon nanomaterials such as nanoparticles or nanotubes. The n-type semiconductor materials can be doped with an n-type dopant, such as nitrogen, to reduce the work function of the semiconductor material, thus decreasing the forward voltage drop of the diode. For instance, graphite powder having a diameter of 50-800 μm can be used.

In some implementations, n-type semiconductor materials include aluminum-doped zinc oxide (AZO) nanoparticles dispersed in deionized water. For example, a ratio of AZO nanoparticles dispersed in deionized water can be 1:50. Nanoparticle size distribution in the n-type semiconductor material may depend, in part, on cost considerations related to generating the n-type electron conducting paint. Nanoparticle size distribution can be selected to optimize light absorption and minimize light scattering for a particular solar spectrum (e.g., AM 1.5G) within the paint layer including the nanoparticles.

Conductive paints prepared according to the process FIG. 2 can include p-type semiconductor materials as the conductive material, e.g., for use as a p-type hole conducting paint layer. Examples of p-type semiconductor materials include p-type hole-conducting nanomaterials (e.g., copper(II) oxide nanoparticles, copper(I) oxide nanoparticles, and nickel(II) oxide nanoparticles). In some examples, a dispersant material, such as benzenesulfonic acid or sodium dodecyl sulfate, can be added to the water phase of the conductive paint to facilitate dispersion of the p-type semiconductor material in the water.

In some implementations, a p-type semiconductor material includes copper oxide nanoparticles dispersed in solvent in a 1:1 ratio. Nanoparticle size distribution in the p-type semiconductor material may depend, in part, on cost considerations related to the p-type hole conducting paint. Nanoparticle size distribution can range from tens of nanometers to several micrometers in diameter and can be selected to optimize light absorption and minimize light scattering for a particular solar spectrum (e.g., AM 1.5G) within the paint layer including the nanoparticles, for a solar paint circuit where the p-type semiconductor material is transparent. In some implementations, paint layers including the p-type semiconductor material are not transparent.

Implementations of solar paints can also include semiconductor paint and photosensitized dye paint. In some implementations, photosensitizing paint layers can combine two or more paint formulations including a semiconductor paint and a photosensitized dye paint to form the photosensitized paint layer, discussed below in more detail with reference to FIG. 8.

Semiconductor paint can include an electron acceptor and a solution for dispersing the electron acceptor. Electron acceptors for a particular semiconductor paint layer can be selected, in part, based on an injection efficiency of the electron acceptor relative to a photosensitizer used in the particular photosensitized dye paint layer. Examples of suitable electron acceptors include titanium dioxide (e.g., rutile or anatase titanium dioxide nanoparticles), zinc oxide, benzothiadiazole, benzotriazole, quinoxaline, phthalimide, diketopyrrolopyrrole, thienopyrazine, thiazole, triazine, cyanovinyl, cyano- and fluoro-substituted phenyl, iodine, rhodanine, naphthalamide, and acrylic acids. In one example, titanium dioxide nanoparticles may be used as electron acceptors in a semiconductor paint. Size distribution of the titanium dioxide nanoparticles may depend, for example, on the desired surface area of the nanoparticles, moiety of the semiconductor paint, and thermodynamic stability of the semiconductor paint layer.

Various different dyes can be used to create photosensitized dye paint. Selection of the dyes used to create photosensitized dye paint can depend in part on an optimal absorption spectrum (e.g., within a specified range) for a particular application (e.g., tropical vs. arctic latitude, indoor vs. outdoor use). Additionally, a photosensitized dye paint can include one or more different dyes for multiple-peak absorption spectra functionality. In some implementations, the dye has high absorption (e.g., in the 500 nm range, which corresponds to a dark bluish-green color), and has at least one chromophore (functional group which is the source of the color/photoactive response) which undergoes excitation from a p to a p* highest-occupied molecular orbital (HOMO) on illumination. Examples of suitable dyes include copper phthalocyanine, zinc phthalocyanine, merocyanine, ruthenium-polypyridine, iron hexacyanoferrate, Ru-polypyridyl-complex sensitizers (e.g., cis-dithiocyanato bis(4,4′-dicarboxy-2,2′-bipyridine)ruthenium(II)).

FIG. 3 is a flow chart of another example process for producing solar paint. Referring to FIG. 3, a semiconductor paint can be prepared by process 300. In 302, semiconductor nanomaterial (e.g., titanium dioxide nanoparticles) is dispersed in a solution (e.g., denatured alcohol or deionized water and a surfactant) to yield a semiconductor paint. In 304, the semiconductor paint can optionally be agitated (e.g., in an ultrasonic bath or stirred) and filtered (e.g., through a microfiber cloth) to evenly disperse the semiconductor nanomaterial in the solution.

FIG. 4 is a flow chart of another example process for producing solar paint. Referring to FIG. 4, photosensitizing paint can be prepared by process 400. In 402, a suitable dye is combined with solvent (e.g., denatured alcohol) to yield a photosensitizing paint. In one example, a photosensitizing paint includes copper phthalocyanine in a weight ratio of anhydrous ethanol:copper phthalocyanine of 1:1.

Example Process for Producing Solar Paint Circuit

FIG. 5 is a flow chart of an example process 500 for painting a solar paint circuit. In general, a solar paint circuit (e.g., solar paint circuit 100) can be fabricated according to process 500, as shown in the flow diagram in FIG. 5. In 502, a substrate is provided. Substrates can include metal, wood, plaster, fabric, or the like. A substrate can further include a wire mesh or foil affixed to a base structural material, to provide electrical conductivity. In 504, one or more paint layers are applied to a surface of the substrate, where each paint layer includes a conductive paint formulation. In some implementations, each applied paint layer is allowed to dry prior to the application of a subsequent layer. In some implementations, each applied paint layer may include a formulation having one or more solvents that are allowed to evaporate prior to the application of a subsequent layer.

A conductive paint layer applied using the conductive paint formulation has a resistance defined, in part, by the resistivity of the conductive material included in the conductive paint formulation. For example, a conductive paint layer applied using conductive paint formulation including a first conductive material (e.g., a conductive nanomaterial) having a higher resistivity provides a higher resistance than a conductive paint layer applied using a conductive paint formulation including a second different conductive material having a lower resistivity.

In some implementations, multiple coatings of a same conductive paint formulation can be applied to form a layer of a desired thickness, where the desired thickness is greater than a thickness of a single applied layer. Each coating of the same conductive paint may be allowed to dry prior to the application of a subsequent layer.

In some implementations, one or more dimensions of the substrate (e.g., aluminum foil) are selected to maximize charge mobility and/or for ease of manufacturing of the solar paint circuit (e.g., roll-to-roll processing). Paint layers may be applied to a roughened surface of the aluminum foil to improve adhesion of the paint to the substrate, maximize a number of charge carriers available at the substrate surface, and/or increase the surface area of the substrate in contact with the applied paint layers. In one example, a substrate is a long thin strip of aluminum foil.

In some implementations, one or more dimensions of the substrate (e.g., aluminum foil) are selected to optimize a cost-per-power-output for the solar paint circuit (e.g., solar cell) efficiency. Though the term “optimize” is used here in reference to a particular scenario where a cost-per-power output is minimized, other “optimized” scenarios may be possible depending on a desired outcome (e.g., low environmental impact, accessibility of materials, minimal manufacturing steps, etc.). Thus, the use of the terms “optimize,” “optimal,” or other similar terms as used herein do not refer to a single optimal outcome.

In one example of a solar cell design that is optimized for cost-per-power output and for a selected length of the solar cell (e.g., selected based on a manufacturing process or dimensions of an installation location), a width of the solar cell can be determined using the following procedure. In this example, it is assumed that a solar cell manufactured with these specifications is used in consistent ambient conditions (e.g., a regular amount of absorbable light energy and spectral distribution of the light energy). It is also assumed that a dominant source of shunt resistance is a transparent outer conductive layer (e.g., n-type electron conducting layer) of the solar cell, for example, that an electrode connecting the solar cell to an external circuit is highly conductive.

A width-independent photoconversion efficiency can be determined for a solar cell, where the solar cell includes an electrical contact with a top shunt electrode that is consistent along a length of the cell and located on one side of the solar cell, by covering the solar cell with an opaque barrier parallel to the top shunt electrode and measuring the power output per unit of expose surface area for the solar cell. Dividing the power output per unit of exposed surface area by an input energy (I_in) in units of power per surface area (e.g., watts per square meter) yields the solar cell efficiency. Width-independent photoconversion efficiencies (e) can be found for multiple solar cells each having different widths and a simple linear regression (e.g., e_total=e_wi−we_loss) can be used to determine the power loss per unit of width (w) such that a y-intercept of the linear regression is a width-independent photoconversion efficiency of the solar cell (ew_i).

For a selected length of solar cell (e.g., selected based on a manufacturing process or dimensions of an installation location), a known cost per unit area (c_area), and a known cost per unit area of the electrodes (c_electrode), a solar cell width to optimize the cost per power output (C_power) of the solar cell can be determined by a ratio of the solar cell cost (C_cell) to the solar cell power output (I_out).

$\begin{array}{cc}{C}_{\mathrm{cell}}\left(w\right)={\mathrm{wlc}}_{\mathrm{area}}+{\mathrm{lc}}_{\mathrm{electrode}}& \left(1\right)\\ I_{\mathrm{out}}\left(w\right)=I_{\mathrm{in}}{\mathrm{wle}}_{\mathrm{wi}}-I_{\mathrm{in}}{\mathrm{we}}_{\mathrm{loss}}& \left(2\right)\\ C_{\mathrm{power}}\left(w\right)=\frac{C_{\mathrm{cell}}\left(w\right)}{I_{\mathrm{out}}\left(w\right)}& \left(3\right)\\ C_{\mathrm{power}}\left(w\right)=\frac{{\mathrm{wlc}}_{\mathrm{area}}+{\mathrm{lc}}_{\mathrm{electrode}}}{I_{\mathrm{in}}{\mathrm{wle}}_{\mathrm{wi}}-I_{\mathrm{in}}{\mathrm{we}}_{\mathrm{loss}}}& \left(4\right)\end{array}$

The derivatives of C_cell(w) and I_out(w) can be found.

C _cell′(w)=lc_area   (5)

I _out′(w)=I_inle_wi−I_ine_loss   (6)

C_power′(w) can be solved algebraically for positive, real values of C_power′(w)=0, by substituting the known values of the constants to find the optimal solar cell width.

$\begin{array}{cc}{C}_{\mathrm{power}}^{\prime }\left(w\right)=\frac{C_{\mathrm{cell}}^{\prime }\left(w\right)I_{\mathrm{out}}\left(w\right)-C_{\mathrm{cell}}\left(w\right)I_{\mathrm{out}}^{\prime }\left(w\right)}{I_{\mathrm{out}}^2\left(w\right)}& \left(7\right)\\ C_{\mathrm{power}}^{\prime }\left(w\right)=\frac{\begin{array}{c}\left({\mathrm{lc}}_{\mathrm{area}}\right)\left(I_{\mathrm{in}}{\mathrm{wle}}_{\mathrm{wi}}-I_{\mathrm{in}}{\mathrm{we}}_{\mathrm{loss}}\right)-\\ \left({\mathrm{wlc}}_{\mathrm{area}}+{\mathrm{lc}}_{\mathrm{electrode}}\right)\left(I_{\mathrm{in}}{\mathrm{le}}_{\mathrm{wi}}-I_{\mathrm{in}}e_{\mathrm{loss}}\right)\end{array}}{{\left(I_{\mathrm{in}}{\mathrm{wle}}_{\mathrm{wi}}-I_{\mathrm{in}}{\mathrm{we}}_{\mathrm{loss}}\right)}^2}& \left(8\right)\end{array}$

FIG. 6 is a flow chart of another example process 600 for painting a solar paint circuit. Referring to FIG. 6, a solar paint circuit (e.g., solar paint circuit 100) can be fabricated according to process 600. Substrates can be electrically conducting or electrically non-conducting. Suitable electrically insulating substrates include wood, plaster, and plastic. Electrically conducting substrates can include substrates having relatively low work-function, low financial cost, low susceptibility to oxidation, and high physical strength relative to the one or more paint layers. Suitable electrically conducting substrates include aluminum mesh, aluminum foil, as well as zinc, magnesium, nickel, copper, silver, gold, and platinum.

In 602, p-type hole conducting paint is applied to a substrate and allowed to dry to yield a layer of the p-type hole conducting paint in direct contact with the substrate. In some implementations, one or more additional layers of the p-type hole conducting paint can be subsequently applied. In some implementations, the one or more layers of p-type hole conducting paint are subsequently sintered. The sintering process for the one or more p-type hole conducting paint layers is discussed in more detail below with reference to FIG. 7.

In 604, photosensitizing paint is applied to the to the p-type hole conducting paint layer and allowed to dry to yield a layer of the photosensitizing paint in direct contact with the layer of the p-type hole conducting paint. In some implementations, one or more additional layers of the photosensitizing paint can be subsequently applied. The one or more layers of photosensitizing paint can be subsequently sintered. The sintering process for the one or more photosensitizing paint layers is discussed in more detail below with reference to FIG. 8.

In some implementations, the photosensitizing paint layer includes a semiconductor paint layer and a photosensitized dye paint layer, where the semiconductor paint layer is applied to the p-type hole conducting paint layer to yield a semiconductor paint layer in direct contact with the layer of the p-type hole conducting paint, and the photosensitized dye paint is applied to the semiconductor paint layer to yield a photosensitized dye paint layer in direct contact with the semiconductor paint layer. The semiconductor paint layer and photosensitized dye paint layer combine to form a photosensitized paint layer, described in more detail below with reference to FIG. 8.

In 606, n-type electron conducting paint is applied to the photosensitizing paint layer and allowed to dry to yield a layer of the n-type electron conducting paint in direct contact with the layer of the photosensitizing paint layer. In some implementations, one or more additional layers of the n-type electron conducting paint can be subsequently applied. In some implementations, the one or more layers of n-type electron conducting paint are subsequently sintered. The sintering process for the one or more n-type electron conducting paint layers is discussed in more detail below with reference to FIG. 9. The n-type electron conducting paint layer is typically transparent. In some implementations, the p-type hole conducting layer is transparent in addition to or in place of the n-type electron conducting layer being transparent.

In 608, a transparent protective paint is applied to the n-type electron conducting paint layer and allowed to dry to yield a layer of the transparent protective paint in direct contact with the n-type electron conducting paint layer. In some implementations, one or more additional layers of the transparent protective paint can be subsequently applied. The transparent protective paint can additionally be applied to exposed surfaces of the solar paint circuit (e.g., solar paint circuit 100) such that the solar paint circuit is encapsulated within a transparent protective coating.

FIG. 7 is a flow chart of an example process 700 for painting a p-type hole conducting paint layer (e.g., p-type hole conducting paint layer 104). In one example, the p-type hole conducting paint includes p-type nanoparticles dispersed in solution. In 702, a layer of the p-type nanoparticles (e.g., copper oxide nanoparticles) dispersed in solution (e.g., denatured alcohol) are applied to a substrate (e.g., substrate 102). Applying the p-type nanoparticles dispersed in solution may be done using an atomizing sprayer or other aerosolized dispersing technique for evenly distributing the p-type nanoparticle solution onto the substrate.

In 704, the solution of the p-type hole conducting paint is evaporated. In some implementations, the solution may be evaporated in ambient conditions. The substrate and/or a surface of the substrate may be locally heated (e.g., with a heat gun, infrared lamp, or other localized heating source) as the p-type nanoparticle paint is applied to the surface of the substrate in order to evaporate the solution (e.g., solvent) or other fluid medium. A temperature of the localized heating can be selected based in part on the evaporation temperature of the particular solution used in the p-type hole conducting paint (e.g., a boiling temperature of water or solvent).

In some implementations, multiple applications of the p-type nanoparticles dispersed in solution are applied and subsequently the solution is evaporated to form multiple layers of the p-type hole conducting paint on the substrate. A number of applications of the p-type hole conducting paint onto the substrate may depend on a desired thickness of the p-type hole conducting paint layer in a direction perpendicular to the surface of the substrate. The desired thickness may be determined, for example, by cost of materials and/or a desired number of charge carriers available for generation/recombination in the p-type hole conducting paint layer. In one example, multiple applications of the p-type hole conducting paint are applied such that the p-type hole conducting paint is several hundred microns thick in a direction perpendicular to the surface of the substrate.

In 706, the p-type hole conducting paint is sintered to form an electrically continuous p-type hole conducting paint layer. A sintering process may include heating the p-type hole conducting paint layer using a furnace, a rapid thermal processing (RTP) system, or other heating source for a period of time until the p-type nanoparticles of the p-type hole conducting paint layers agglomerate into an electrically continuous layer (e.g., as measured by a four-point probe or other resistance measurements), and/or a structurally continuous layer (e.g., as measured by ellipsometry or other optical inspection). A range of combinations of temperatures and durations for a sintering process may be appropriate to achieve an electrically continuous p-type hole conducting layer, and may depend in part on a type of sintering process (e.g., a tool or system) used. In some implementations, a selected temperature and duration of the sintering process for the p-type hole conducting layer depends on cost-considerations, equipment limitations, and/or design limitations (e.g., thermal budget) of other paint layers in the solar paint circuit.

FIG. 8 is a flow chart of an example process 800 for painting a photosensitized paint layer. In one example, a process for painting a photosensitized paint layer includes a first step for painting a layer of semiconductor paint onto the p-type hole conducting paint layer and a second step for painting a photosensitizer dye paint onto the semiconductor paint layer.

In 802, a layer of semiconductor paint (e.g., semiconductor nanoparticles dispersed in solution) is applied to the p-type hole conducting paint layer. The semiconductor nanoparticles can be, for example, titanium dioxide nanoparticles that are dispersed in denatured alcohol or deionized water and a surfactant (e.g., sodium dodecyl sulfate).

Applying the semiconductor paint may be done using an atomizing sprayer or other aerosolized dispersing technique for evenly distributing the semiconductor paint onto the p-type hole conducting paint layer.

In 804, the solution of the semiconductor paint layer is evaporated. In some implementations, the solution (e.g., deionized water, denatured alcohol, or another solvent) may be evaporated in ambient conditions. The p-type hole conducting layer, substrate, or both may be locally heated (e.g., with a heat gun or other localized heating source) as the semiconductor paint is applied to the surface of the p-type hole conducting layer in order to evaporate the solution (e.g., solvent or other fluid medium) of the semiconductor paint layer. A temperature of the localized heating can be selected based in part on the evaporation temperature of the particular solution used in the semiconductor particle paint (e.g., a boiling temperature of water or solvent).

In some implementations, multiple applications of the semiconductor paint are applied and subsequently the solution medium (e.g., solvent) is evaporated to form multiple layers of the semiconducting paint on top of the p-type hole conducting paint layer. Multiple layers of the semiconducting paint can be applied to the p-type hole conducting paint layer until the semiconducting paint layer completely covers the p-type hole conducting paint layer in a uniform and continuous layer. In some implementations, a number of semiconducting paint layers applied to the p-type hole conducting paint layer is selected to be the fewest possible number of semiconductor paint layers while still forming an electrically continuous and/or structurally continuous film on top of the p-type hole conducting paint layer. A thickness of the p-type hole conducting paint layer in a direction perpendicular to a surface of the substrate can be in the nanometer to micrometer range.

In 806, the semiconductor paint layer is sintered to form an electrically continuous semiconductor paint layer. A sintering process may include heating the semiconductor paint layer using a furnace, a rapid thermal processing (RTP) system, or another heating source for a period of time until the semiconductor nanoparticles agglomerate into an electrically continuous layer (e.g., as measured by a four-point probe or other resistance measurements). A range of combinations of temperatures and durations for a sintering process may be appropriate to achieve an electrically continuous semiconductor paint layer, and may depend in part on a type of sintering process (e.g., a tool or system) used. In some implementations, a selected temperature and duration of the sintering process for the semiconductor paint layer depends on cost-considerations, equipment limitations, and/or design limitations (e.g., thermal budget) of other paint layers in the solar paint circuit.

In 808, a photosensitized dye paint is applied to the semiconductor paint layer. In some implementations, the photosensitized dye paint includes a photosensitized dye (e.g., copper phthalocyanine) dispersed in solution (e.g., anhydrous ethanol or other denatured alcohol).

The photosensitized dye paint can be applied to the semiconductor paint layer using an atomizing sprayer or other aerosolized dispersing technique for evenly distributing the photosensitized dye paint onto the semiconductor paint layer. In some implementations, a particular aerosolized dispersing technique for applying the photosensitized dye paint is selected to minimize a size of droplets of the paint during the application to the semiconductor paint layer.

In 810, the solution of the photosensitized dye paint layer is evaporated. In some implementations, the solution (e.g., deionized water, denatured alcohol, or another solvent) may be evaporated in ambient conditions. The semiconductor paint layer, the p-type hole conducting paint layer, substrate, or a combination thereof may be locally heated (e.g., with a heat gun or other localized heating source) as the photosensitized dye paint is applied to the surface of the semiconductor paint layer in order to evaporate the solvent or other fluid medium of the photosensitized dye paint layer. A temperature of the localized heating can be selected based in part on the evaporation temperature of the particular solution used in the photosensitized dye paint (e.g., a boiling temperature of water or solvent).

In some implementations, multiple applications of the photosensitized dye is applied to the semiconductor paint layer and subsequently the solution medium (e.g., solvent) is evaporated to form multiple layers of the photosensitized dye paint on the semiconductor paint layer. In some implementations, multiple layers of the photosensitized dye paint are applied to the semiconductor paint layer until visual inspection of the photosensitized dye paint layer appears blue-green in color. Other forms of optical and/or visual inspection of the layer are possible, for example, using ellipsometry or a camera including machine-learning image recognition software.

In 812, the photosensitized dye paint layer is thermally processed (e.g., by thermal annealing, or by photonic curing) to chemisorb the photosensitized dye paint layer onto the semiconductor paint layer (e.g., to chemisorb the phthalocyanine onto the titanium dioxide surface) to form the photosensitized paint layer. A thermal treatment process may include heating the semiconductor paint layer in a furnace, rapid thermal processing (RTP) system, pulsed light from a flashlamp, or other heating source for a period of time until the photosensitized dye is chemisorbed onto the surface of the semiconductor paint layer. The temperature and duration of the thermal anneal may be selected such that the chemisorbed photosensitized dye is resistant to heat degradation under the normal operating conditions of the solar paint circuit (e.g., under ambient conditions including UV exposure). A range of combinations of temperatures and durations for the thermal anneal may be appropriate to achieve a fully chemisorbed photosensitized dye layer, and may depend in part on a type of anneal process (e.g., a tool or system) used. In some implementations, a selected temperature and duration of the thermal anneal for the photosensitized dye layer depends on cost-considerations, equipment limitations, and/or design limitations (e.g., thermal budget) of other paint layers in the solar paint circuit.

FIG. 9 is a flow chart of an example process 900 for painting an n-type electron conducting paint layer. In 902, a layer of n-type nanoparticles (e.g., aluminum-doped zinc oxide nanoparticles) dispersed in solution (e.g., a solvent) are applied to the photosensitized paint layer (e.g., on a top surface of the photosensitized dye paint layer). Applying the n-type nanoparticles dispersed in solution may be done using an atomizing sprayer or other aerosolized dispersing technique for evenly distributing the n-type nanoparticle solution onto the photosensitized dye paint layer.

In 904, the solution of the n-type electron conducting paint layer is evaporated. In some implementations, the solution may be evaporated in ambient conditions. The photosensitized dye paint layer, the semiconductor paint layer, the p-type hole conducting paint layer, substrate, or a combination thereof may be locally heated (e.g., with a heat gun, infrared lamp, or other localized heating source) as the n-type nanoparticle paint is applied to the surface of the photosensitized dye paint layer in order to evaporate the solution (e.g., solvent or other fluid medium). A temperature of the localized heating can be selected based in part on the evaporation temperature of the particular solution used in the n-type electron conducting paint (e.g., a boiling temperature of water or solvent).

In some implementations, multiple applications of the n-type electron conducting paint are applied and subsequently the solution is evaporated to form multiple layers of the n-type electron conducting paint on a surface of the photosensitized dye paint layer. In some implementations, multiple layers of the n-type electron conducting paint are applied to the photosensitized dye paint layer until the transparency of the n-type electron conducting paint layer begins to decrease. The transparency of the n-type electron conducting paint layer may be determined, for example, by visual inspection, ellipsometry, or a camera including machine-learning image recognition software. In some implementations, the transparency of the n-type electron conducting paint layer can be determined by measuring a conversion efficiency of a solar paint circuit including the n-type electron conducting paint layer (e.g., solar paint circuit 100) and comparing it to a conversion efficiency of a known, well-performing solar cell (e.g., a commercially-available silicon solar cell).

In 906, the n-type electron conducting paint is sintered to form an electrically continuous n-type electron conducting paint layer. A sintering process may include heating the n-type electron conducting paint layer using a furnace, a rapid thermal processing (RTP) system, an infrared lamp, or another heating source for a period of time until the n-type nanoparticles agglomerate into an electrically continuous layer (e.g., as measured by a four-point probe or other resistance measurements) and/or a structurally continuous layer (e.g., as determined by ellipsometry or other form of optical inspection). Sintering conditions (e.g., temperature and duration) can be selected to minimize an amount of desorption of the photosensitized dye paint layer while still forming an electrically continuous n-type electron conducting paint layer. A range of combinations of temperatures and durations for a sintering process may be appropriate to achieve an electrically continuous n-type electron conducting layer, and may depend in part on a type of sintering process (e.g., a tool or system) used. In some implementations, a selected temperature and duration of the sintering process for the n-type electron conducting layer depends on cost-considerations, equipment limitations, and/or design limitations (e.g., thermal budget) of other paint layers in the solar paint circuit.

In some implementations, the solar paint circuit (e.g., solar paint circuit 100) is annealed after the n-type electron conducting paint is applied and thermally processed (e.g., by photonic curing). A low-temperature anneal (e.g., 145° C.) may be performed on the solar painted circuit to mitigate migration or desorption of the photosensitized dye paint layer (e.g., phthalocyanine) from the semiconductor paint layer (e.g., titanium dioxide nanoparticle layer) during the fabrication process.

In some implementations, contacts are affixed to the top and bottom of the solar painted circuit (e.g., contact 112). Contacts may be fixed to the solar painted circuit using a conductive glue, a conductive foil coated with laminate, or the like. The two contacts can be selected each of a different metal having a different work function (e.g., a steel contact and a copper contact) such that the flow of electricity is determined by the respective work functions of the two contacts.

In some implementations, a transparent protective coating (e.g., plastic laminate, polyurethane varnish) is applied to the exposed surfaces (e.g., a top surface of the n-type electron conducting layer) of the solar painted circuit.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any features or of what can be claimed, but rather as descriptions of features specific to particular embodiments of the described painted circuits and painted circuit elements. Though the painted circuits and painted circuit elements examples are described herein as having particular layer structures, they should not be read as limiting. For example, the painted circuits and painted circuit elements are described as operating in a “top-down” fashion where the devices are painted layer-by-layer such that the top layer is the top of the device. While processes are depicted in the drawings in a particular order, this should not be understood as requiring that such processes be performed in the particular order shown or in sequential order, or that all illustrated processes be performed, to achieve desirable results. For example, the painted circuits and painted circuit elements may also be painted in a “bottom-up” fashion where the function of the devices is upside relative to their fabrication order. Additionally, “flip-chip” configurations can be imagined where two substrates are individually painted with paint layers and then combined.

Other complex painted circuit elements can be created using the techniques and compositions described herein. For example, painted antenna elements. Additionally, active matrices of multiple smaller sub-elements (e.g., embedded painted circuit elements) can be created using the techniques and compositions described herein.

Thus, particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous.

Claims

1. A painted circuit, comprising: a substrate; andone or more paint layers applied to the substrate, wherein the one or more paint layers each form an electrical component of the painted circuit, the one or more paint layers including: a p-type hole conducting paint layer applied to the substrate;a photosensitized paint layer applied to the p-type hole conducting paint layer;an n-type electron conducting paint layer applied to the photosensitized paint layer; anda transparent protective paint layer applied to the n-type electron conducting paint layer.

2. The painted circuit of claim 1, wherein a given paint layer of the one or more paint layers comprises a conductive paint formulation having a resistance that is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and a thickness of the given paint layer, and wherein the resistance of the conductive paint formulation including a conductive material having a higher resistivity provides a higher resistance than the resistance of the conductive paint formulation including a conductive material with a lower resistivity.

3. The painted circuit of claim 1, wherein the p-type hole conducting paint layer comprises p-type nanoparticles.

4. The painted circuit of claim 3, wherein the p-type nanoparticles are copper oxide nanoparticles.

5. The painted circuit of claim 1, wherein the photosensitized paint layer comprises a semiconductor paint layer and a photosensitized dye paint layer.

6. The painted circuit of claim 5, wherein the semiconductor paint layer comprises a titanium dioxide nanoparticles.

7. The painted circuit of claim 5, wherein the photosensitized dye paint layer comprises copper phthalocyanine.

8. The painted circuit of claim 1, wherein the n-type electron conducting paint layer comprises n-type nanoparticles.

9. The painted circuit of claim 8, wherein the n-type nanoparticles are aluminum-doped zinc oxide nanoparticles.

10. The painted circuit of claim 1, further comprising two or more contacts, each contact comprising a metallic foil affixed to a substrate or an n-type electron conducting paint layer and in electrical contact with the substrate or the n-type electron conducting paint layer, respectively.

11. A process for manufacturing a painted circuit, comprising: providing a substrate; andapplying one or more paint layers on a surface of the substrate, the one or more paint layers each forming an electrical component of the painted circuit, wherein applying the one or more paint layers includes: applying a p-type hole conducting paint to the substrate to yield a layer of the p-type hole conducting paint in direct contact with the substrate;applying a photosensitized paint to the p-type hole conducting paint layer to yield a layer of the photosensitized paint in direct contact with the p-type hole conducting layer;applying an n-type electron conducting paint to the photosensitized paint layer to yield a layer of the n-type electron conducting paint in direct contact with the photosensitized paint layer; andapplying a transparent protective paint to the n-type electron conducting paint layer to yield a layer of the transparent protective paint in direct contact with the n-type electron conducting paint layer.

12. The process of claim 11, wherein a given paint layer of the one or more paint layers comprises a conductive paint formulation having a resistance that is defined in part by a resistivity of a conductive material that is included in the conductive paint formulation and a thickness of the given paint layer, and wherein the resistance of the conductive paint formulation including a conductive material having a higher resistivity provides a higher resistance than the resistance of the conductive paint formulation including a conductive material with a lower resistivity.

13. The process of claim 11, wherein applying a p-type hole conducting paint comprises applying a layer of p-type nanoparticles dispersed in solution on the substrate, and sintering the p-type nanoparticles to form an electrically continuous p-type hole conducting paint layer.

14. The process of claim 13, wherein the p-type nanoparticles are copper oxide nanoparticles.

15. The process of claim 11, wherein applying a photosensitized paint comprises: applying a layer of semiconductor paint including semiconductor nanoparticles dispersed in solution on the p-type hole conducting paint layer;sintering the semiconductor nanoparticles to form an electrically continuous semiconductor paint layer;applying a layer of photosensitized dye paint to the semiconductor paint layer; andthermally processing the photosensitized dye paint layer to chemisorb the photosensitized dye paint layer onto the semiconductor paint layer.

16. The process of claim 15, wherein the semiconductor nanoparticles are titanium dioxide nanoparticles.

17. The process of claim 15, wherein the photosensitized dye is copper phthalocyanine in anhydrous ethanol.

18. The process of claim 11, wherein applying an n-type electron conducting paint comprises applying a layer of n-type nanoparticles dispersed in solution on the photosensitized paint layer, and sintering the n-type nanoparticles to form an electrically continuous n-type electron conducting paint layer.

19. The process of claim 18, wherein the n-type nanoparticles are aluminum-doped zinc oxide nanoparticles.

20. The process of claim 11, further comprising thermally processing the painted circuit.

21. The process of claim 11, further comprising affixing two or more contacts to the painted circuit, wherein each contact comprises a metallic foil and is affixed to a substrate or an n-type electron conducting layer and in electrical contact with the substrate or the n-type electron conducting layer, respectively.