JP2013522879A - Photovoltaic module with buffer layer - Google Patents

Abstract

A photovoltaic module including a buffer layer, and associated photovoltaic cells, articles, systems, and methods are disclosed.

Description

  The present invention relates to a photovoltaic module including a buffer layer, and related photovoltaic cells, articles, systems and methods.

  Photovoltaic cells are commonly used to convert energy in the form of light into energy in the form of electricity. A typical photovoltaic cell includes a photoactive material disposed between two electrodes. In general, light passes through one or both electrodes and interacts with the photoactive material, thereby generating charged particles (ie, electrons and holes).

  It is an object of the present invention to provide a photovoltaic module including a buffer layer, as well as associated photovoltaic cells, articles, systems and methods.

  In the photovoltaic cell, when a buffer layer containing one or more specific polymers is provided between the barrier layer and the electrode, the mechanical stress on the electrode is reduced, and the barrier layer is further separated from the electrode to the interlayer. Based on the unexpected discovery that peeling can be prevented. This delamination leads to a significant decrease in the performance of the photovoltaic cell. The buffer layer can further serve as a barrier that prevents any adhesive between the barrier layer and the electrode and oxygen or moisture in the environment from diffusing through the electrode to the photovoltaic cell. As a result, a photovoltaic module including such a buffer layer can improve long-term stability and increase the usable life.

  In one aspect, the invention is supported by a first photovoltaic cell having a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode; A photovoltaic module comprising: a barrier layer; an adhesive layer containing an adhesive; and a buffer layer containing a polymer selected from the group consisting of polyurethane, polyolefin, polyvinyl butyral, ionomer polymers or copolymers thereof. And The first electrode is between the barrier layer and the photoactive layer. The adhesive layer is between the first electrode and the barrier layer. The buffer layer is between the first electrode and the adhesive layer.

  In another aspect, the invention is supported by a first photovoltaic cell having a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode; And a buffer layer containing a polymer comprising a polyolefin grafted with anhydride, acid, or acrylate. The first electrode is between the barrier layer and the photoactive layer. The buffer layer is between the first electrode and the barrier layer. The module does not have an additional adhesive layer between the buffer layer and the barrier layer.

Embodiments can include one or more of the following optional features.
Polymers include polyolefins grafted with anhydrides, acids, or acrylates; polyethylene waxes; ethylene-maleic anhydride copolymers; ethylene-methacrylic acid copolymers or salts thereof; polyisobutylenes or polyols (eg, polyether polyols) , Polyester polyols, neopentyl polyols and cyclopentane polyols); and diisocyanates (eg, toluene diisocyanates).

The polymer may have a glass transition temperature of at least about 80 ° C. and / or at most about 120 ° C.
The polymer may be present from about 70% to about 100% by weight of the buffer layer.
The buffer layer may further include a filler such as nanoclay. Nanoclays can include montmorillonite, kaolinite, llite or chlorite. In some embodiments, the filler may be present from about 0% to about 30% by weight of the buffer layer.

The buffer layer can substantially cover the entire region between the first electrode and the adhesive layer or, if there is no adhesive layer, the entire region between the first electrode and the barrier layer.
The module may include a second photovoltaic cell that is separated from the first photovoltaic cell, the separation being performed by an interconnect region for electrically connecting the first photovoltaic cell and the second photovoltaic cell. In such embodiments, the buffer layer can cover the interconnect region.

  The module can include a plurality of photovoltaic cells, each having a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode. In such an embodiment, the buffer layer may be between the first electrode of each photovoltaic cell and the adhesive layer, and the buffer is the entire buffer area between the first electrode of each photovoltaic cell and the adhesive layer. The area can be substantially covered.

The buffer layer and the adhesive layer, or the buffer layer and the barrier layer can have a first adhesive strength, and the buffer layer and the first electrode have a second adhesive strength greater than the first adhesive strength. Can do.
The buffer layer may have a water vapor transmission rate of at most about 0.01 g / m ² / day.
The buffer layer may have a thickness of about 25 micrometers (about 25 microns) to about 250 micrometers (about 250 microns).

The adhesive may contain an epoxy resin.
The barrier layer may include at least two (eg, at least three) polymer layers and at least two ceramic layers between the at least two polymer layers.

The barrier layer can include a metal foil.
Polyolefins can include homopolymers or copolymers.
The polyolefin may include polyethylene, polypropylene, ethylene vinyl acetate copolymer, or ethylene acrylate copolymer.

  The buffer layer consists of low density polyethylene grafted with anhydride; linear low density polyethylene grafted with anhydride; high density polyethylene grafted with anhydride; polypropylene grafted with anhydride; anhydride or acid. Grafted ethylene acrylate copolymers; and ethylene vinyl acetate copolymers grafted with anhydrides, acids or acrylates.

  Other features and advantages of the invention will be apparent from the description and drawings, and from the claims.

It is sectional drawing of embodiment of the photovoltaic module containing a photovoltaic cell and a buffer layer. 1 is a cross-sectional view of an embodiment of a photovoltaic module including a plurality of photovoltaic cells and a buffer layer. 1 is a cross-sectional view of an embodiment of a photovoltaic module that includes a plurality of photovoltaic cells and a buffer layer, the buffer layer covering an interconnection region between the photovoltaic cells. It is a graph which shows the series resistance change of various photovoltaic modules in a moisture-proof heat-resistant aging process. It is a graph which shows the efficiency change of various photovoltaic modules in a moisture-proof heat-resistant aging process. It is a graph which shows the curve factor change of various photovoltaic modules in a moisture-resistant heat-resistant aging process.

Like reference symbols refer to like parts throughout the various drawings.
FIG. 1 shows a cross-sectional view of a photovoltaic module 100 that includes a photovoltaic cell 101, a buffer layer 170, an optional adhesive layer 180, and a barrier layer 190. The photovoltaic cell 101 includes a substrate 110, an electrode 120, an optional hole blocking layer 130, a photoactive layer 140 (eg, including an electron acceptor material and an electron donor material), an optional hole carrier layer 150, and an electrode 160. including. As shown in FIG. 1, the buffer layer 170 substantially covers the entire region between the electrode 160 and the adhesive layer 180 or between the electrode 160 and the barrier layer 190 (in the absence of the adhesive layer 180).

  In general, the buffer layer 170 is formed from one or more polymers. Typical polymers suitable for use in the buffer layer 170 include polyurethane, polyolefin, polyvinyl butyral, ionomer polymers or copolymers thereof.

  Typical polyurethanes include those made from diisocyanates (eg, toluene diisocyanate) and polyols (polyether polyols, polyester polyols, neopentyl polyols and cyclopentane polyols). Commercially available examples of suitable polyurethanes include Epoxies, Etc. L020910 available from the company (Cranston, RI) and D9940-0401 available from Epic Resins (Palmyra, Wis.).

As used herein, the term “polyolefin” refers to a homopolymer or copolymer made from at least linear or branched, cyclic or acyclic olefin monomers. Examples of polyolefin homopolymers include polyethylene, polypropylene, polybutene, polypentene and polymethylpentene. In addition to being formed from olefins, polyolefin copolymers can be formed from olefin monomers and one or more comonomers. Typical comonomers that can be used to make polyolefin copolymers include vinyl acetate or acrylates (eg, alkyl acrylates such as methyl acrylate, ethyl acrylate or butyl acrylate, or methyl methacrylate, ethyl methacrylate). Or alkyl methacrylates such as butyl methacrylate). Typical polyolefin copolymers include ethylene vinyl acetate copolymers and ethylene acrylate copolymers. In some embodiments, as a typical polyethylene homopolymer or polyethylene copolymer, low density polyethylene (eg, having a density of 0.910 g / cm ^{2 to} 0.925 g / cm ² ), linear low density polyethylene ^(e.g., 0.910 g / cm 2 having a density of ~0.935g / cm ²⁾ include and high density polyethylene ^(e.g., having a density of ^{0.935g / cm 2 ~0.970g / cm 2} ) . High density polyethylene can be produced by copolymerization of ethylene with one or more C4 to C20 alpha olefin comonomers. Examples of suitable alpha olefin comonomers include 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene and combinations thereof. High density polyethylene can contain up to 20 mole percent of the aforementioned alpha olefin comonomer.

In some embodiments, polyolefins suitable for the buffer layer 170 include polyolefins grafted with anhydrides, acids or acrylates; polyethylene waxes; ethylene-maleic anhydride copolymers; ethylene-methacrylic acid copolymers or salts thereof; And polyisobutylene. The salt of the ethylene-methacrylic acid copolymer may comprise any suitable cation such as Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ and Zn ²⁺ . Commercially available examples of ethylene-methacrylic acid copolymers or salts thereof include E.I. I. du Pont de Nemours and Company, Inc. SURLYN® series of polymers available from (Wilmington, DE).

  In some embodiments, the polyolefin comprises a polyolefin graft copolymer. For example, the polyolefin graft copolymer may comprise a polyolefin grafted with an anhydride, acid or acrylate. Examples of such graft copolymers include: low density polyethylene grafted with anhydride; linear low density polyethylene grafted with anhydride; high density polyethylene grafted with anhydride; grafted with anhydride. Polypropylene; anhydride or acid grafted ethylene acrylate copolymer; and anhydride, acid or acrylate grafted ethylene vinyl acetate copolymer. Commercially available examples of the first polymer include E.I. I. du Pont de Nemours and Company, Inc. BYNEL® series of polymers available from

Ionomeric polymers that can be used in the buffer layer 170 include polymers that contain acid moieties (eg, carboxylic acid moieties, sulfonic acid moieties, or phosphoric acid moieties). The acidic groups in the ionomer polymer can be partially or completely converted to salts containing appropriate cations such as Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ and Zn ²⁺ . Examples of suitable ionomer polymers include polymers containing ethylene copolymer moieties and acid copolymer moieties. The ethylene copolymer portion can be formed by copolymerization of ethylene and a monomer selected from the group consisting of vinyl acetate, alkyl acrylate and alkyl methacrylate. The acid copolymer portion can be formed by copolymerization of ethylene and a monomer selected from the group consisting of acrylic acid and methacrylic acid. Other examples include ionomer polyvinyl butyral such as those described in US Pat. No. 4,968,745.

  While not wishing to be bound by theory, the inventors have described one of the above-described ones as the buffer layer 170 between the electrode 160 and the adhesive layer 180 or between the electrode 160 and the barrier layer 190. Alternatively, it has been surprisingly discovered that the use of multiple polymers can reduce mechanical stress on the electrode 160 and further prevent the barrier layer 190 from delaminating from the electrode 160. This delamination leads to a significant decrease in the performance of the photovoltaic cell 101. The polymer described above can further serve as a barrier to prevent the adhesive in the adhesive layer 180 and the oxygen or water in the environment from diffusing through the electrode 160 to the photovoltaic cell 101. As a result, the photovoltaic module 101 has improved long-term stability and increased usable life.

In some embodiments, a polymer suitable for use in the buffer layer 170 has a glass transition temperature (T _g ) that is sufficiently low that the buffer layer 170 is mechanically more flexible than the barrier layer 190, and It has a sufficiently high T _g so as to have a relatively high adhesive strength with the electrode 160. For example, the polymer may be at most about 120 ° C. (eg, at most about 115 ° C., at most about 110 ° C., at most about 105 ° C., or at most about 100 ° C.), and / or at least about 80 ° C. ( For example, it may have a glass transition temperature of at least about 85 ° C., at least about 90 ° C., at least about 95 ° C., or at least about 100 ° C.).

  In some embodiments, the buffer layer 170 contains at least about 70% (eg, at least about 75%, at least about 80%, at least about 85%, or at least about one or more polymers as described above. About 90% by weight) and / or at most about 100% by weight (eg at most about 99% by weight, at most about 95% by weight, at most about 90% by weight, or at most about 85% by weight). .

  In some embodiments, the buffer layer 170 may include a filler, such as an inorganic filler such as nanoclay. Nanoclays can include clays from the smectite family. Smectite nanoclays have a unique morphology and are characterized by one dimension (eg, thickness) in the nanometer range (eg, about 1 nm to about 100 nm). An example of a smectite nanoclay is montmorillonite. Other examples of nanoclays include kaolinite, illite or chlorite. All nanoclays described herein can be obtained from commercial sources (eg, Nanocor, Inc.). Although not wishing to be bound by theory, it is believed that when the buffer layer 170 includes a filler (such as those described above), diffusion of oxygen or moisture in the environment to the photovoltaic cell 101 can be prevented. It is done.

  In some embodiments, the buffer layer 170 contains at least about 1% by weight of the filler described above (eg, at least about 5%, at least about 10%, at least about 15%, or at least about 20%). And / or at most about 30% by weight (eg, at most about 25% by weight, at most about 20% by weight, at most about 15% by weight, or at most about 10% by weight).

  In some embodiments, the filler (eg, nanoclay) is baked at a sufficiently low temperature before being added to the buffer layer 170. For example, the filler may be at most about 70 ° C. (eg, at most about 65 ° C., at most about 60 ° C., at most about 55 ° C., or about 50 ° C.), and / or at least about 30 ° C. (eg, low At about 35 ° C., at least about 40 ° C., at least about 45 ° C., or at least about 50 ° C.). While not wishing to be bound by theory, it is believed that baking the filler at the temperatures described above can reduce or eliminate the mass of nanoclay particles. This lump increases haze and may reduce the light transmittance to the photovoltaic cell 101.

  In some embodiments, the buffer layer 170 and the adhesive layer 180, or the buffer layer 170 and the barrier layer 190 (in the absence of the adhesive layer 180) can have a first adhesive strength and the buffer layer 170. And the electrode 160 may have a second adhesive strength greater than the first adhesive strength. The adhesion strength referred to herein is measured by a T-peel test according to ASTM D 1876-01. While not wishing to be bound by theory, it is believed that such a buffer layer can reduce or prevent delamination of the barrier layer 190 from the electrode 160.

In general, the buffer layer 170 has a sufficiently low water vapor transmission rate (MVTR) to prevent diffusion of environmental moisture or oxygen into the photovoltaic cell 101. The MVTR described herein is measured according to ASTM E-96. For example, the buffer layer 170 is about 0.01 g / ^{m 2} / day (e.g., at most about 0.005 g / ^{m 2} / day at most, at most about 0.001 g / ^{m 2} / day, at most about 0. (0005 g / m ² / day, or at most about 0.0001 g / m ² / day).

  In some embodiments, the buffer layer 170 has at most about 250 micrometers (about 250 microns) (eg, at most about 225 micrometers (about 225 microns), at most about 200 micrometers (about 200 microns), At most about 175 micrometers (about 175 microns), or at most about 150 micrometers (about 150 microns), and / or at least about 25 micrometers (about 25 microns) (eg, at least about 50 micrometers (about 50 microns), at least about 75 microns (about 75 microns), at least about 100 microns (about 100 microns), or at least about 125 microns (about 125 microns)).

  In general, the buffer layer 170 can be attached to the electrode 160 by methods known in the art or as described herein. For example, the buffer layer 170 may be a preformed film that includes one or more of the polymers described above and an optional filler (eg, nanoclay). This film can be formed by a known method (for example, film extrusion). After the film is formed, the film can be pressed against the electrode 160 such that the film adheres to the electrode 160.

  In some embodiments, the buffer layer 170 can be formed on the electrode 160 by an extrusion coating process. For example, if the buffer layer 170 includes SURLYN® polymer, the SURLYN® polymer can be melted and introduced into the extruder. The molten polymer can then be discharged from the extruder and applied onto the electrode 160. In such embodiments, a filler (eg, nanoclay) can be optionally mixed with the molten polymer in the extruder to form a mixture, which is then discharged from the extruder and the electrode 160 Can be applied on top.

  In some embodiments, the buffer layer 170 is a solution coating, ink jet printing, spin coating, dip coating, knife coating, bar coating, spray coating, roller coating, slot coating, gravure coating, flexographic coating, other than extrusion coating process. It can be formed on the electrode 160 by a coating process such as printing or screen printing. For example, the buffer layer 170 may include (1) mixing a polymer (eg, polyurethane) and an optional filler (eg, nanoclay) with a solvent (eg, water or an organic solvent) to form a solution or dispersion; It can be formed by 2) applying a solution or dispersion on the electrode 160 and (3) drying the applied solution or dispersion.

  In some embodiments, the buffer layer 170 can be formed using one of the solvent-free coating processes described in the previous paragraph. For example, if the buffer layer 170 comprises polyurethane, it can be: (1) mixing a diisocyanate monomer with a polyol monomer or prepolymer in the absence of a solvent to form a mixture; (2) placing the mixture on the electrode 160; And (3) to form the buffer layer 170 by polymerizing the monomers in the mixture (eg, by heating). In certain embodiments, a solvent can be added during the mixing step to facilitate mixing the diisocyanate monomer with the polyol monomer or prepolymer.

  In some embodiments, the photovoltaic modules described herein include a plurality of photovoltaic cells and a buffer layer that substantially covers the entire area between the electrodes of each photovoltaic cell and the adhesive or barrier layer. Including. FIG. 2 shows a cross-sectional view of a photovoltaic module 200 that includes a plurality of photovoltaic cells 201, a buffer layer 270, an optional adhesive layer 280, and a barrier layer 290. Each photovoltaic cell 201 includes an electrode 220, an optional hole blocking layer 230, a photoactive layer 240, an optional hole carrier layer 250 and an electrode 260. The photovoltaic cells 201 share a common substrate 210 and are separated from each other by an interconnect region 202, which can be used for electrical connection between the photovoltaic cells. As shown in FIG. 2, the buffer layer 270 covers the entire area between the electrode 260 and the adhesive layer 280 of each photovoltaic cell 201 or between the electrode 260 and the barrier layer 290 (when there is no adhesive layer 280). Substantially covering. Further, the buffer layer 270 covers the interconnect region 202.

  In some embodiments, the photovoltaic modules described herein include a plurality of photovoltaic cells and a buffer layer that substantially covers an interconnect region between the photovoltaic cells only. FIG. 3 shows a cross-sectional view of a photovoltaic module 300 that includes a plurality of photovoltaic cells 301, a buffer layer 370, an optional adhesive layer 380 and a barrier layer 390. Each photovoltaic cell 301 includes an electrode 320, an optional hole blocking layer 330, a photoactive layer 340, an optional hole carrier layer 350 and an electrode 360. The photovoltaic cells 301 share a common substrate 310 and are separated from each other by an interconnect region 302 that can be used for electrical connection between the photovoltaic cells. As shown in FIG. 3, the buffer layer 370 substantially covers only the interconnect region 302.

  In general, the optional adhesive layer 180 includes an adhesive to adhere the barrier layer 190 to the photovoltaic cell 101. A typical adhesive is an epoxy resin. The adhesive layer 180 can be made by a method known in this technical field. In some embodiments, the adhesion layer 180 can be formed by applying a layer comprising an epoxide monomer and a comonomer (eg, polyamine) onto the surface of the barrier layer 190 and then curing the monomer by heating. In some embodiments, the adhesion layer 180 applies a layer comprising an epoxide monomer and an initiator (eg, acid or base) onto the surface of the barrier layer 190 and then cures the monomer by ultraviolet light through a ring-opening polymerization reaction. Can be formed. The article thus formed can then be attached to the buffer layer 170 to form the photovoltaic module 100.

  In some embodiments, the adhesive layer 180 can be omitted from the photovoltaic module 100. For example, if the buffer layer 170 is formed from a polyolefin grafted with an anhydride, acid or acrylate (such as those described above), the adhesive layer 180 can be omitted. This is because such polyolefins can form strong adhesive bonds to both the barrier layer 190 and the electrode 160. In some embodiments, the polyolefin can be formed on the buffer layer 170 by melting the polyolefin and extruding the hot melt onto the buffer layer.

  In general, the barrier layer 190 is made of a material that can sufficiently prevent the diffusion of oxygen or moisture in the environment into the photovoltaic cell 101. In some embodiments, the barrier layer 190 has a multilayer structure and includes at least two (eg, at least three) polymer layers (eg, each comprising a polyester, such as polyethylene terephthalate or polyethylene naphthalate). And having a composite comprising at least two ceramic layers (eg each comprising silica or alumina) between at least two polymer layers. In such an embodiment, the barrier layer 190 may have three polymer layers and two ceramic layers in the following order: polymer layer, ceramic layer, polymer layer, ceramic layer, and polymer layer.

  In some embodiments, the barrier layer 190 is made from a transparent material (eg, the multilayer structure described in the previous paragraph). As quoted herein, a transparent material is at least about 60% of incident light at the thickness or range of wavelengths used during operation of the photovoltaic cell, at the thickness used in the photovoltaic cell 101. (Eg, at least about 70%, at least about 75%, at least about 80%, at least about 85%).

  In some embodiments, the barrier layer 190 may include a metal foil. Without wishing to be bound by theory, metal foils are generally considered to be better barrier materials than composite materials formed from polymers and ceramics. On the other hand, metal foils are generally less transparent than composite materials formed from polymers and ceramics, so one side of the photovoltaic module 100 (eg, the bottom surface of the photovoltaic module 100 where incident light cannot normally reach). Usually used only above.

  For photovoltaic cell 101, substrate 110 may generally be formed from a transparent material. Typical materials from which the substrate 110 can be formed include polyethylene terephthalate, polyimide, polyethylene naphthalate, hydrocarbon polymers, cellulosic polymers, polycarbonates, polyamides, polyethers and polyether ketones. In some embodiments, the polymer may be a fluorinated polymer. In some embodiments, a combination of polymeric materials is used. In some embodiments, different regions of the substrate 110 can be formed from different materials.

In some embodiments, the substrate can be made from an opaque material such as a metal foil.
In general, the substrate 110 can be flexible, semi-rigid or rigid (eg, glass). In some embodiments, the substrate 110 has a flexural modulus of less than about 5,000 megapascals (eg, less than about 1,000 megapascals, or less than about 500 megapascals). In some embodiments, different regions of the substrate 110 can have flexibility, semi-rigidity, or inflexibility (eg, one or more regions are flexible and one or more other regions). Semi-rigid, one or more regions are flexible and one or more other regions are inflexible).

  Typically, the substrate 110 has a thickness of at least about 1 micrometer (about 1 micron) (eg, at least about 5 micrometers (about 5 microns), or at least about 10 micrometers (about 10 microns)). And / or a thickness of at most about 1,000 micrometers (about 1,000 microns) (eg, at most about 500 micrometers (about 500 microns), at most about 300 micrometers (about 300 microns), At most about 200 micrometers (about 200 microns), at most about 100 micrometers (about 100 microns), or at most about 50 micrometers (about 50 microns)).

  In general, the substrate 110 can be colored or uncolored. In some embodiments, one or more portions of the substrate 110 are colored while one or more other portions of the substrate 110 are uncolored.

  The substrate 110 can have one flat surface (eg, a surface that is exposed to light) or two flat surfaces (eg, a surface that is exposed to light and the opposite surface), or can have a non-planar surface. . The non-planar surface of the substrate 110 can be bent or stepped, for example. In some embodiments, the non-planar surface of the substrate 110 is patterned (eg, with patterned steps to form a Fresnel lens, lenticular lens, or lenticular prism).

  In some embodiments, the substrate 110 can be the same as the barrier layer 190 and can be attached to the electrode 120 by an adhesive (such as that used in the adhesive layer 180). In such embodiments, the material used in the buffer layer 170 can also be included between the electrode 120 and the adhesive. In some embodiments, the adhesive is omitted when the buffer layer includes a material that can form a strong cohesive bond with both substrate 110 and electrode 120 (eg, polyolefin grafted with anhydride, acid or acrylate). can do.

  The electrode 120 is generally formed from a conductive material. Typical conductive materials include conductive metals, conductive alloys, conductive polymers, and conductive metal oxides. Typical conductive metals include gold, silver, copper, aluminum, nickel, palladium, platinum and titanium. Typical conductive alloys include stainless steel (eg, 332 stainless steel, 316 stainless steel), gold alloy, silver alloy, copper alloy, aluminum alloy, nickel alloy, palladium alloy, platinum alloy, and titanium alloy. Typical conductive polymers include polythiophene (eg, doped poly (3,4-ethylenedioxythiophene) (doped PEDOT), polyaniline (eg, doped polyaniline), polypyrrole (eg, doped polypyrrole). Typical conductive metal oxides include indium tin oxide, fluorinated tin oxide, tin oxide, and zinc oxide, hi some embodiments, a combination of conductive materials is used.

  In some embodiments, the electrode 120 can include a mesh electrode. Examples of mesh electrodes are described in co-pending US Patent Application Publication Nos. 20040187911 and 20060090791.

In some embodiments, combinations of the materials described above can be used to form the electrode 120.
Optionally, the photovoltaic cell 101 can include a hole blocking layer 130. The hole blocking layer is generally formed from a material that transports electrons to the electrode 120 and substantially blocks hole transport to the electrode 120 at the thickness used in the photovoltaic cell 101. Examples of materials that can form the hole blocking layer include LiF, metal oxides (eg, zinc oxide, titanium oxide) and amines (eg, primary amine, secondary amine, tertiary amine). Examples of amines suitable for use in the hole blocking layer are described, for example, in co-pending US Patent Application Publication No. 2008-0264488.

  Without wishing to be bound by theory, when the photovoltaic cell 101 includes a hole blocking layer made from an amine, the hole blocking layer is not exposed to ultraviolet light, and the photoactive layer 140 and the electrode 120 It is believed that the formation of ohmic contacts can be promoted, thereby reducing damage to the photovoltaic cell 101 due to ultraviolet exposure.

  Typically, the hole blocking layer 130 is at least about 0.02 micrometers (about 0.02 microns) (eg, at least about 0.03 micrometers (about 0.03 microns), at least about 0.04 micrometers). (About 0.04 micron), or at least about 0.05 micrometer (about 0.05 micron)) and / or at most about 0.5 micrometer (about 0.5 micron) (e.g. At most about 0.4 micrometers (about 0.4 microns), at most about 0.3 micrometers (about 0.3 microns), at most about 0.2 micrometers (about 0.2 microns), or more Both are about 0.1 micrometers (about 0.1 microns) thick.

Photoactive layer 140 is generally formed from an electron acceptor material (eg, an organic electron acceptor material) and an electron donor material (eg, an organic electron donor material).
In some embodiments, the electron donor material can include a photoactive polymer (eg, a conjugated polymer) containing one or more of the following monomer repeat units: a benzodithiophene moiety, a cyclopentadithiazole moiety. Benzothiadiazole moiety, thiadiazoloquinoxaline moiety, benzoisothiazole moiety, benzothiazole moiety, dithienopyrrole moiety, dibenzosilole moiety, thienothiophene moiety, carbazole moiety, dithienothiophene moiety, tetrahydroisoindole moiety, fluorene moiety, silole moiety, Cyclopentadithiophene moiety, thiazole moiety, selenophene moiety, thiazolothiazole moiety, naphthothiadiazole moiety, thienopyrazine moiety, silacyclopentadithiophene moiety, thiophene moiety, Xazole, imidazole, pyrimidine, benzoxazole, benzimidazole, quinoxaline, pyridopyrazine, pyrazinopyridazine, pyrazinoquinoxaline, thiadiazolopyridine, thiadiazolopyridazine, benzooxadiazole An oxadiazolopyridine moiety, an oxadiazolopyridazine moiety, a benzoselenadiazole moiety, a benzobisoxazole moiety, a thienothiadiazole moiety, a thienopyrroledione moiety, or a tetrazine moiety. The “moieties” mentioned above are one or more halo (eg, F, Cl, Br, or I), C ₁ -C ₂₄ alkyl, C ₁ -C ₂₄ alkoxy, aryl, heteroaryl, C ₃ -C _{24 cycloalkyl,} C 3 _{-C 24} heterocycloalkyl, COR, COOR, CO-N (RR '), CN , or can be replaced by SO ₃ R, wherein, R and R' of each is _{independently, H,} C 1 _{-C 24} alkyl, aryl, _heteroaryl, C 3 _{-C 24} cycloalkyl or _C 3 _{-C 24} heterocycloalkyl,. The photoactive polymer can be a homopolymer or a copolymer comprising two or more of the above monomer repeat units.

In some embodiments, the electron acceptor material of the photoactive layer 140 can include fullerene. In some embodiments, the photoactive layer 140 can include one or more unsubstituted fullerenes and / or one or more substituted fullerenes. Examples of unsubstituted fullerenes include C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , C ₈₂ , C ₈₄ and C ₉₂ . Examples of substituted fullerenes are fullerenes substituted with phenylbutyric acid methyl esters (PCBMs such as C61-PCBM and C71-PCBM); or fullerenes substituted with C ₁ -C ₂₀ alkoxy, or optionally C ₁ include; -C ₂₀ alkoxy, and / or halo (halo) _{(e.g., (OCH 2 CH 2) 2} OCH 3 or _{OCH 2 CF 2 OCF 2 CF 2} OCF 3) fullerene, which is further substituted with. While not wishing to be bound by theory, fullerenes replaced with long chain alkoxy groups (eg oligomeric ethylene oxide) or fluorinated alkoxy groups have improved solubility in organic solvents and improved. It is considered that a photoactive layer having a different shape can be formed. Other examples of fullerenes are described, for example, in co-pending US Patent Application Publication No. 2005-0279399 by the same rights holder. In some embodiments, the electron acceptor material can include one or more of the photoactive polymers described in the previous paragraph. In some embodiments, a combination of electron acceptor materials (eg, the fullerenes and photoactive polymers described above) can be used in the photoactive layer 140.

  Other examples of electron donor materials and electron accepting materials are described, for example, in US Pat. Nos. 7,772,485 and 7,781,673 by the same rights holder, Patent Application Publication Nos. 2007-0017571, 2007-0020526, 2008-0087324, 2008-0121281, 2010-0032018, and international It is described in the application PCT / US2011 / 020227 pamphlet.

  In general, the thickness of the photoactive layer 140 is large enough to absorb incident light to generate electrons and holes, and allow the generated electrons or holes to be transported to adjacent layers. Should be small enough to do. Typically, the thickness of the photoactive layer 140 is at least about 50 micrometers (about 50 microns) (eg, at least about 75 micrometers (about 75 microns), at least about 100 micrometers (about 100 microns), at least about 125 micrometers. Micrometer (about 125 microns), at least about 150 microns (about 150 microns), or at least about 200 microns (about 200 microns)) and / or at most about 300 microns (about 300 microns) ( For example, at most about 250 micrometers (about 250 microns), at most about 200 micrometers (about 200 microns), or at most about 150 micrometers (about 150 microns)).

  Optionally, the photovoltaic cell 101 can include a hole carrier layer 150. The hole carrier layer 150 is generally formed from a material that transports holes to the electrode 160 and substantially prevents transport of electrons to the electrode 160 at the thickness used in the photovoltaic cell 101. Examples of materials that can form layer 150 include polythiophene (eg, PEDOT), polyaniline, polycarbazole, polyvinylcarbazole, polyphenylene, polyphenylvinylene, polysilane, polythienylene vinylene, polyisothiaphthalene, and their co-polymers Coalescence is mentioned. In some embodiments, the hole carrier layer 150 can include a dopant used in combination with one of the above materials. Examples of dopants include poly (styrene sulfonate), polymeric sulfonic acids or fluorinated polymers (eg, fluorinated ion exchange polymers).

  In some embodiments, the material that can be used to form the hole carrier layer 150 includes a metal oxide such as titanium oxide, zinc oxide, tungsten oxide, molybdenum oxide, copper oxide, strontium copper oxide, or strontium titanium oxide. Is mentioned. The metal oxide may be undoped or doped with a dopant. Examples of dopants for metal oxides include fluoride, chloride, bromide and iodide salts or acids.

  In some embodiments, materials that can be used to form the hole carrier layer 150 include carbon allotropes (eg, carbon nanotubes). The carbon allotrope can be embedded in the polymeric binder.

In some embodiments, the hole carrier material can be in the form of nanoparticles. The nanoparticles can take any suitable shape, such as a spherical, cylindrical, or rod shape.
In some embodiments, the hole carrier layer 150 can include a combination of the hole carrier materials described above.

  In general, the thickness of the hole carrier layer 150 (ie, the distance between the surface of the hole carrier layer 150 in contact with the photoactive layer 140 and the surface of the electrode 160 in contact with the hole carrier layer 150) varies as desired. be able to. Typically, the thickness of the hole carrier layer 150 is at least about 0.01 micrometer (about 0.01 micron) (eg, at least about 0.05 micrometer (about 0.05 micron), at least about 0.1 micron. 1 micrometer (about 0.1 micron), at least about 0.2 micrometer (about 0.2 micron), at least about 0.3 micrometer (about 0.3 micron), or at least about 0.5 micrometer ( And / or at most about 5 micrometers (about 5 microns) (eg, at most about 3 micrometers (about 3 microns), at most about 2 micrometers (about 2 microns)) ), Or at most about 1 micrometer (about 1 micron)). In some other embodiments, the thickness of the hole carrier layer 150 is between about 0.01 micrometers (about 0.01 microns) to about 0.5 micrometers (about 0.5 microns).

  Electrode 160 is generally formed from a conductor material, such as one or more conductor materials described above with respect to electrode 120. In some embodiments, the electrode 160 is formed from a combination of conductor materials. In some embodiments, the electrode 160 can be formed from a mesh electrode. In other embodiments, the electrode 160 is a metal nanoparticle dispersed in a polymer matrix, such as that disclosed in co-pending U.S. Patent Application Publication No. 2008-0236657 by the same rights holder (e.g., Silver nanorods).

  In general, the method of fabricating each layer of the photovoltaic cell 101 described above may vary as desired. In some embodiments, the layer can be made by a liquid-based coating process. In some embodiments, the layer can be made by a vapor phase based coating process, such as a chemical vapor deposition process or a physical vapor deposition process.

  As used herein, the term “liquid-based coating process” refers to a process using a liquid-based coating composition. Examples of liquid-based coating compositions include solutions, dispersions, or suspensions. The liquid-based coating process is at least one of the following steps: solution coating, ink jet printing, spin coating, dip coating, knife coating, bar coating, spray coating, roller coating, slot coating, gravure coating, flexographic printing or screen printing. This can be done by using. An example of a liquid-based coating process is described, for example, in co-pending US Patent Application Publication No. 2008-0006324 by the same rights holder.

  In some embodiments, when the layer includes inorganic semiconductor nanoparticles, the liquid-based coating process includes (1) combining the nanoparticles with a solvent (eg, an aqueous solvent or absolute alcohol) to form a dispersion. It can be carried out by mixing, (2) applying the dispersion on the substrate, and (3) drying the applied dispersion. In some embodiments, the liquid-based coating process to make a layer comprising inorganic metal oxide nanoparticles is (1) a precursor in a suitable solvent (eg, anhydrous alcohol) to form a dispersion. (For example, titanium salt) is dispersed, (2) the dispersion is coated on the substrate, (3) the dispersion is hydrolyzed to form an inorganic semiconductor nanoparticle layer (for example, titanium oxide nanoparticle layer). It can be carried out by decomposing and (4) drying the inorganic semiconductor material oxide film. In some embodiments, the liquid-based coating process can be performed by a sol-gel method (eg, by forming metal oxide nanoparticles as a sol-gel in the dispersion before applying the dispersion on the substrate).

  In general, the liquid-based coating process used to make the layer containing the organic semiconductor material can be the same as or different from the process used to make the layer containing the inorganic semiconductor material. In some embodiments, to create a layer comprising an organic semiconductor material, the liquid-based coating process mixes the organic semiconductor material with a solvent (eg, an organic solvent) to form a solution or dispersion. It can be carried out by applying a solution or dispersion on a substrate and drying the applied solution or dispersion.

  In some embodiments, the photovoltaic cell 101 can be made in a continuous manufacturing process, such as a roll-to-roll process, thereby significantly reducing manufacturing costs. An example of a roll-to-roll process is described, for example, in co-pending US Patent Application Publication No. 2005-0263179 by the same rights holder.

  In general, in use, incident light can strike the surface of the substrate 110 and pass through the substrate 110, the electrode 120, and the optional hole blocking layer 130. The light then interacts with the photoactive layer 140 such that electrons are transferred from the electron donor material (eg, conjugated polymer) to the electron acceptor material (eg, substituted fullerene). The electron acceptor material then sends electrons through the optional hole blocking layer 130 to the electrode 120 and the electron donor material sends holes through the hole carrier layer 150 to the electrode 160. Electrodes 120 and 160 are in electrical continuity through an external load so that electrons pass from electrode 120 through the load to electrode 160. When the barrier layer 190, the adhesive layer 180, and the buffer layer 170 are transparent, incident light can also pass through these layers and interact with the photoactive layer 140 that generates electrons and holes.

While some specific embodiments have been disclosed, other embodiments are possible.
In some embodiments, the photovoltaic cell 101 may be co-pending U.S. Patent Application Publication Nos. 2007-0246094, 2007-0181179, 2007-0272296, and A tandem photovoltaic cell such as that described in the specification of the above-mentioned 2009-0211633 may be used.

  In some embodiments, the photovoltaic cell 101 includes a cathode as the lower electrode and an anode as the upper electrode. In some embodiments, the photovoltaic cell 101 can include an anode as a lower electrode and a cathode as an upper electrode.

  In some embodiments, the photovoltaic cell 101 can include the layers shown in FIG. 1 in reverse order. In other words, the photovoltaic cell 101 moves these layers from bottom to top in the following order: barrier layer 190, adhesive layer 180, buffer layer 170, electrode 160, optional hole carrier layer 150, photoactive layer 140, An optional hole blocking layer 130, electrode 120 and substrate 110 can be included.

  In some embodiments, photovoltaic module 100 includes a plurality of photovoltaic cells 101 that are electrically connected in series. In some embodiments, the photovoltaic module 100 includes a plurality of photovoltaic cells 101 that are electrically connected in parallel. In some embodiments, some photovoltaic cells 101 in the photovoltaic module 100 are electrically connected in series, and some photovoltaic cells 101 in the photovoltaic module 100 are electrically connected in parallel. The

  Although an organic photovoltaic cell has been described, other photovoltaic cells can also be included in the photovoltaic module 100 described herein. Examples of such photovoltaic cells are inorganic photoactive with dye-sensitized photovoltaic cells and photoactive materials made of amorphous silicon, cadmium selenide, cadmium telluride, copper indium selenide, and copper indium gallium selenide A battery is mentioned. In some embodiments, a hybrid photovoltaic cell can be included in the photovoltaic module 100 described herein.

  Although described for photovoltaic cells, in some embodiments, the buffer layers described herein can be used in other devices and systems. For example, the buffer layer can be a field effect transistor, a photodetector (eg, an IR detector), a photovoltaic detector, an imaging device (eg, an RGB imaging device for a camera or diagnostic imaging system), a light emitting diode (LED ) (Eg, organic LEDs (OLEDs) or infrared or near infrared LEDs), laser devices (lasing devices), conversion layers (eg, layers that convert visible light emission to infrared light emission), amplifiers for remote communication And suitable organic semiconductor devices such as emitters (eg, fiber dopants), storage elements (eg, holographic storage elements), and electrochromic devices (eg, electrochromic displays).

The contents of all publications cited herein (eg, patents, patent application publications, and articles) are hereby incorporated by reference in their entirety.
The following examples are illustrative and not limiting.

  The following six photovoltaic modules were prepared: (1) A photovoltaic module having no buffer layer and containing poly (3-hexylthiophene) as a photoactive polymer (“OPV Gen I without buffer layer”) (2) Photovoltaic module having a buffer layer containing SURLYN (R) 1702 and containing poly (3-hexylthiophene) as a photoactive polymer ("OPV Gen I SURLYN (R) 1702 with buffer layer") ), (3) Photovoltaic module having a buffer layer containing polyurethane and containing poly (3-hexylthiophene) as a photoactive polymer (“OPV Gen I coatable buffer layer”), (4) Buffer Photovoltaic module ("OPV Ge" which does not have a layer and contains polysilacyclopentadithiophene copolymer as a photoactive polymer. II, no buffer layer ”), (5) a photovoltaic module having a buffer layer containing SURLYN® 1702 and containing a polysilacyclopentadithiophene copolymer as a photoactive polymer (“ OPV Gen II SURLYN ( R) with 1702 buffer layer ”), and (6) Photovoltaic module (“ OPV Gen II coatable ”with a buffer layer comprising polyurethane and comprising polysilacyclopentadithiophene copolymer as photoactive polymer There is a buffer layer ").

  Each module includes 10 photovoltaic cells interconnected by using a continuous coating process. The photovoltaic cell was made by the method described in Example 6 of co-pending U.S. Patent Application Publication No. 2008-0087324 by the same rights holder. The module was packaged as follows.

  Each of modules (1) and (4) was made by first attaching interconnected photovoltaic cells to both electrode terminals with copper tape. Next, a material containing a curable epoxide of 10 to 20 micrometers (10 to 20 microns) was applied to both sides of the interconnected photovoltaic cells and laminated with a transparent barrier film. Subsequently, the article thus formed was cured at 70 ° C. to 100 ° C. for 5 minutes to form a module (1) or (4).

  Each of modules (2) and (5) was made by first attaching interconnected photovoltaic cells to both electrode terminals with copper tape. Next, 50.8 to 254 micrometers (2 to 10 mils) of SURLYN® 1702 films were hot laminated on both sides of the interconnected photovoltaic cells using a heated laminator. Subsequently, a material containing a curable epoxide of 10 to 20 micrometers (10 to 20 microns) was applied to the SURLYN® 1702 film and laminated with a transparent barrier film. Next, the article thus formed was cured at 70 ° C. to 100 ° C. for 5 minutes to form a module (2) or (5).

  Each of modules (3) and (6) was made by first attaching interconnected photovoltaic cells to both electrode terminals with copper tape. Next, a mixture containing diisocyanate and polyol was applied to both sides of the interconnected photovoltaic cells, and cured at 70 ° C. to form a buffer layer. Subsequently, a curable epoxide-containing material of 10 to 20 micrometers (10 to 20 microns) was applied to the buffer layer and laminated with a transparent barrier film. Next, the article thus formed was cured at 70 ° C. to 100 ° C. for 5 minutes to form a module (3) or (6).

  Modules (l)-(6) were tested for stability in a high temperature and high humidity oven at 65 ° C. and 85% relative humidity (RH). Module performance was measured using simulated sunlight under AM 1.5 conditions. During testing, the modules were periodically removed from the oven, measured for their performance, and returned to the oven. The test results are shown in FIGS.

  As shown in FIGS. 4-6, the series resistance, efficiency, and fill factor of modules (1) and (4) deteriorated significantly after about 100 days at 65 ° C. and 85% relative humidity. Surprisingly, the series resistance, efficiency, and fill factor of modules (2), (3), (5), and (6) remain relatively constant after over 400 days at 65 ° C. and 85% relative humidity. Met.

  Other embodiments are within the scope of the claims.

Claims (36)

A first photovoltaic cell having a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode;
A barrier layer supported by the first photovoltaic cell, wherein the first electrode is between the barrier layer and the photoactive layer;
An adhesive layer containing an adhesive, and between the first electrode and the barrier layer;
A buffer layer comprising a polymer selected from the group consisting of polyurethane, polyolefin, polyvinyl butyral, ionomer polymer, or copolymers thereof, and between the first electrode and the adhesive layer;
Comprising a module.   The polymer was made from anhydride, acid or acrylate grafted polyolefin, polyethylene wax, ethylene-maleic anhydride copolymer, ethylene-methacrylic acid copolymer or salt thereof, polyisobutylene, or polyol and diisocyanate. The module of claim 1 comprising polyurethane.   A polyurethane wherein the polymer is made of an ethylene-methacrylic acid copolymer or salt thereof; or toluene diisocyanate and a polyol selected from the group consisting of polyether polyol, polyester polyol, neopentyl polyol and cyclopentane polyol. The module of claim 1, comprising:   The module of claim 1, wherein the polymer has a glass transition temperature of at most about 120 ° C.   The module of claim 1, wherein the polymer has a glass transition temperature of at least about 80 ° C.   The module of claim 1, wherein the polymer is about 70% to about 100% by weight of the buffer layer.   The module of claim 1, wherein the buffer layer further comprises a filler.   The module of claim 7, wherein the filler comprises nanoclay.   The module of claim 8, wherein the nanoclay comprises montmorillonite, kaolinite, illite or chlorite.   The module of claim 7, wherein the filler is about 0% to about 30% by weight of the buffer layer.   The module according to claim 1, wherein the buffer layer substantially covers an entire region between the first electrode and the adhesive layer.   The module according to claim 1 is a second photovoltaic cell, wherein the first photovoltaic cell is separated from the first photovoltaic cell by an interconnection region for electrically connecting the first photovoltaic cell and the second photovoltaic cell. A photovoltaic module, wherein the buffer layer covers the interconnect region.   The module of claim 1 comprises a plurality of photovoltaic cells; each photovoltaic cell has a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode. The buffer layer is between the first electrode and the adhesive layer of each photovoltaic cell; and the buffer area is the entire region between the first electrode and the adhesive layer of each photovoltaic cell. Substantially covering the module. The module of claim 1, wherein the buffer layer has a water vapor transmission rate of at most about 0.01 g / m ² / day.   The module of claim 1, wherein the buffer layer has a thickness of about 25 micrometers (about 25 microns) to about 250 micrometers (about 250 microns).   The module according to claim 1, wherein the adhesive contains an epoxy resin.   The module of claim 1, wherein the barrier layer has at least two polymer layers and at least two ceramic layers between the at least two polymer layers.   The module of claim 1, wherein the barrier layer comprises a metal foil. A first photovoltaic cell having a first electrode and a second electrode, and a photoactive layer between the first electrode and the second electrode;
A barrier layer supported by the first photovoltaic cell, wherein the first electrode is between the barrier layer and the photoactive layer;
A buffer layer having a polymer comprising a polyolefin grafted with an anhydride, acid or acrylate, and between the first electrode and the barrier layer;
A module comprising:
The module does not include an additional adhesive layer between the buffer layer and the barrier layer;
module.   The module of claim 19, wherein the polyolefin comprises a homopolymer or a copolymer.   The module of claim 19, wherein the polyolefin comprises polyethylene, polypropylene, ethylene vinyl acetate copolymer or ethylene acrylate copolymer.   The buffer layer comprises low density polyethylene grafted with anhydride, linear low density polyethylene grafted with anhydride, high density polyethylene grafted with anhydride, polypropylene grafted with anhydride, anhydride or acid. 20. A module according to claim 19, comprising a grafted ethylene acrylate copolymer and an ethylene vinyl acetate copolymer grafted with an anhydride, acid or acrylate.   The module of claim 19, wherein the polymer has a glass transition temperature of at most about 120 ° C.   The module of claim 19, wherein the polymer has a glass transition temperature of at least about 80 ° C.   The module of claim 19, wherein the polymer is about 70% to about 100% by weight of the buffer layer.   The module according to claim 19, wherein the buffer layer further contains a filler.   27. The module of claim 26, wherein the filler comprises nanoclay.   28. The module of claim 27, wherein the nanoclay comprises montmorillonite, kaolinite, illite or chlorite.   27. The module of claim 26, wherein the filler is about 1% to about 30% by weight of the buffer layer.   The module of claim 19, wherein the buffer layer substantially covers an entire area between the first electrode and the barrier layer.   The module according to claim 19 is a second photovoltaic cell, wherein the first photovoltaic cell is separated from the first photovoltaic cell by an interconnection region for electrically connecting the first photovoltaic cell and the second photovoltaic cell. A module comprising: two photovoltaic cells, wherein the buffer layer covers the interconnect region.   The module of claim 19 comprises a plurality of photovoltaic cells; each photovoltaic cell has a first electrode and a second electrode and a photoactive layer between the first electrode and the second electrode. The buffer layer is between the first electrode and the barrier layer of each photovoltaic cell; and the buffer area is the entire region between the first electrode and the barrier layer of each photovoltaic cell. Substantially covering the module. The module of claim 19, wherein the buffer layer has a water vapor transmission rate of at most about 0.01 g / m ² / day.   20. The module of claim 19, wherein the buffer layer has a thickness of about 25 micrometers (about 25 microns) to about 250 micrometers (about 250 microns).   The module of claim 19, wherein the barrier layer has at least two polymer layers and at least two ceramic layers between the at least two polymer layers.   The module of claim 19, wherein the barrier layer comprises a metal foil.