JP2014042083A - Solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell having high reliability.SOLUTION: The solar cell includes a photovoltaic conversion device having a first surface and a second surface facing to the first surface, a first electrode connected to the first surface of the photovoltaic conversion device, a second electrode connected to the second surface of the photovoltaic conversion device, and an alkaline metal-containing layer contacting one of the first and second electrodes. The photovoltaic conversion device is CuInGaSe.

Description

  The present invention relates to a solar cell.

  A solar cell is a photoelectric energy conversion system that converts light energy emitted from the sun into electrical energy. In a solar cell, pairs of electrons and holes are generated inside a semiconductor by incident light, and electrons move to an n-type semiconductor and holes move to a p-type semiconductor by an electric field generated at a pn junction. Power can be produced.

  Solar cells generate power using an infinite solar light source as a source, and no pollution is generated when the power is generated. Therefore, solar cells are attracting attention as a typical future environmental energy source. However, since solar cells have low photoelectric energy conversion efficiency, there are many problems in practical use. Therefore, many studies are underway to increase photoelectric energy conversion efficiency in order to put solar cells into practical use.

US Patent Application Publication No. 2008/0295884

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a solar cell having high reliability.

  Another object of the present invention is to provide a solar cell having high efficiency.

  In order to achieve the above technical problem, the present invention provides a solar cell. The solar cell includes a first surface and a photoelectric conversion element including a second surface opposite to the first surface, a first electrode connected to the first surface of the photoelectric conversion element, and the photoelectric conversion element A second electrode connected to a second surface, the first electrode, and an alkali metal-containing film in contact with any one of the second electrode.

  The alkali metal-containing film is disposed on the second electrode and functions as an antireflection film, and the second electrode may be interposed between the alkali metal-containing film and the photoelectric conversion element.

  The solar cell further includes a glass substrate disposed on the alkali metal-containing film, and an antireflection film disposed on the glass substrate, and the alkali metal-containing film includes the glass substrate and the glass substrate. The glass substrate is disposed between the antireflection film and the alkali metal-containing film, and the refractive index of the alkali metal-containing film is greater than the refractive index of the glass substrate. The refractive index of the second electrode may be smaller.

  The first electrode includes a first surface that contacts the photoelectric conversion element, and a second surface facing the first surface, and the solar cell includes a substrate that covers the second surface of the first electrode; The metal grid may further include a metal grid that penetrates the alkali metal-containing film and contacts the second electrode.

  The solar cell may further include an antireflection film disposed on the alkali metal-containing film, and the metal grid may further penetrate the antireflection film.

  The first electrode includes a first surface in contact with the photoelectric conversion element and a second surface facing the first surface, and the alkali metal-containing film covers the second surface of the first electrode. Can do.

  The solar cell further includes a glass substrate disposed on the second electrode, and an antireflection film disposed on the glass substrate, wherein the glass substrate includes the second electrode and the antireflection film. Can be arranged between.

  The solar cell may further include a metal grid that contacts the first electrode through the alkali metal-containing film.

  In the alkali metal-containing film, the reflectance of the incident light with respect to the first wavelength band is higher than the reflectance with respect to the second wavelength band, and the first wavelength band and the second wavelength band may be different from each other.

  The second wavelength band may include visible light.

  The solar cell may further include an additional alkali metal-containing film disposed on the second electrode, and the second electrode may be disposed between the additional alkali metal-containing film and the photoelectric conversion element. it can.

  The alkali metal-containing film covers an upper surface of the photoelectric conversion element and functions as an antireflection film, and the second electrode penetrates the alkali metal-containing film and is connected to the photoelectric conversion element. (Grid).

  The first electrode includes a first surface in contact with the photoelectric conversion element and a second surface facing the first surface, and the solar cell is an additional alkali metal that covers the second surface of the first electrode. A containing film can be further included.

  The electrode in contact with the alkali metal-containing film may include a halogen element and a group 6 element.

The alkali metal in the alkali metal-containing film can be combined with oxygen or fluorine. Wherein the alkali metal-containing _{film, NaF, NaO, NaAlO 2,} Na 2 O-Al 2 O 3 -nSiO 2 (n is an _{integer), NaBO 2, Na 2 B} 4 O 7, NaBH 4, Na 2 C 2, In the compound state of NaBH ₄ , Na ₂ O ₂ , Na ₂ Si ₂ O ₅ , Na ₂ SiO ₃ , and Na ₄ SiO ₄ , any one alkali metal can be included.

  The amount of the alkali metal in the alkali metal-containing film may be 5 to 20 wt%.

  The first electrode and the second electrode may be transparent and include a conductive material.

  The photoelectric conversion element may include a plurality of PIN diodes.

  The photoelectric conversion element may include a plurality of PN diodes.

The photoelectric conversion element is any one of Si, SiGe, CuInSe, CuInS, CuInGaSe, CuInGaS, CdS, CdTe, ZnO, ZnS, CuZnSnS, CuZnSnSe, Cu ₂ O, GaAs, GaInAs, GaInAlAs, or InP. The alkali metal which is can be included.

  A part of the alkali metal in the alkali metal-containing film may be diffused to the photoelectric conversion element through an electrode in contact with the alkali metal-containing film.

  According to the embodiment of the present invention, the electrode connected to the photoelectric conversion element and the alkali metal-containing film are in contact with each other, and the alkali metal contained in the alkali metal-containing film is diffused into the photoelectric conversion element to photoelectric conversion of the photoelectric conversion element. Efficiency can be increased. Therefore, a solar cell optimized for high efficiency can be provided.

1 is a view for explaining a solar cell according to a first embodiment of the present invention. 1 is a view for explaining a solar cell according to a first embodiment of the present invention. 1 is a view for explaining a solar cell according to a first embodiment of the present invention. 1 is a view for explaining a solar cell according to a first embodiment of the present invention. 5 is a view for explaining a solar cell according to a second embodiment of the present invention. 5 is a view for explaining a solar cell according to a second embodiment of the present invention. 5 is a view for explaining a solar cell according to a second embodiment of the present invention. 5 is a view for explaining a solar cell according to a third embodiment of the present invention. 5 is a view for explaining a solar cell according to a third embodiment of the present invention. 5 is a view for explaining a solar cell according to a third embodiment of the present invention. 6 is a view for explaining a solar cell according to a fourth embodiment of the present invention. 6 is a view for explaining a solar cell according to a fourth embodiment of the present invention. 1 is a diagram for explaining a photoelectric conversion element according to an embodiment of the present invention. 1 is a diagram for explaining a photoelectric conversion element according to an embodiment of the present invention. 1 is a view for explaining a metal grid according to an embodiment of the present invention. 1 is a view for explaining a metal grid according to an embodiment of the present invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein, but may be embodied in other forms. Rather, the embodiments presented herein are provided so that the disclosed content will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art. Or in order to follow a desirable embodiment, the reference numerals presented by the order of explanation are not necessarily limited to the order. In the drawings, the thickness of films and regions are exaggerated for clarity. Or when a film is referred to as being on another film or substrate, it can be formed directly on the other film or substrate, or a third film can be interposed therebetween. In this specification, the expression “and / or” is used to mean that at least one of the constituent elements arranged in the front-rear direction is included.

  A solar cell according to a first embodiment of the present invention will be described. FIG. 1A is a view for explaining a solar cell according to a first embodiment of the present invention.

  Referring to FIG. 1A, a photoelectric conversion element 120 is provided. The photoelectric conversion element 120 generates carriers (for example, holes and electrons) by incident sunlight. The photoelectric conversion element 120 may include a first surface and a second surface facing the first surface. The photoelectric conversion element 120 may include a first conductive semiconductor layer, a second conductive semiconductor layer, and an intrinsic semiconductor layer. The first conductivity type semiconductor layer and the second conductivity type semiconductor layer may be N type semiconductor layers. The intrinsic semiconductor layer may be interposed between the first conductive semiconductor layer and the second conductive semiconductor layer. The first conductive type semiconductor layer may be spaced apart from the second conductive type semiconductor layer. The first conductivity type and the second conductivity type may be different conductivity types. The photoelectric conversion element 120 may include a first conductivity type semiconductor layer and a second conductivity type semiconductor layer. The first conductivity type semiconductor layer may be a P-type semiconductor layer, and the second conductivity type semiconductor layer may be an N-type semiconductor layer.

The first surface and the second surface of the photoelectric conversion element 120 may be surfaces included in semiconductor layers having different conductivity types. For example, the first surface of the photoelectric conversion element 120 is a surface included in an N-type semiconductor layer, and the second surface of the photoelectric conversion element 120 is a surface included in a P-type semiconductor layer. (Surface). The photoelectric conversion element 120 is Si, SiGe, CuInSe, CuInS, CuInGaSe, or CuInGaS, and at least one of CdS, CdTe, ZnO, ZnS, CuZnSnS, CuZnSnSe, Cu ₂ O, GaAs, GaInAs, GaInAlAs, or InP. One can be included. The photoelectric conversion element 120 may include an organic semiconductor material. The photoelectric conversion element 120 may have a multi-junction structure and a HIT (heterojunction with intrinsic thin layer) structure.

  The first surface of the photoelectric conversion element 120 may be connected to the first electrode 110. The first electrode 110 may cover the first surface of the photoelectric conversion element 120. The first electrode 110 may be in direct contact with the first surface of the photoelectric conversion element 120. The second surface of the photoelectric conversion element 120 may be connected to the second electrode 130. The second electrode 130 may cover the second surface of the photoelectric conversion element 120. The second electrode 130 may be in direct contact with the second surface of the photoelectric conversion element 120.

The first electrode 110 may include a metal. For example, the first electrode 110 may include silver Ag, gold Au, platinum Pt, nickel Ni, chromium Cr, aluminum Al, titanium Ti, molybdenum Mo, or tungsten W. In contrast, the first electrode 110 may include a transparent conductive material. For example, the first electrode 110 may include any one of ZnO: Al, ZnO: Ga, ITO, SnO ₂ , SnO: F, RuO ₂ , IrO ₂ , or Cu ₂ O.

The second electrode 130 may include a transparent conductive material. For example, the second electrode 130 is made of ZnO: Al, ZnO: Ga, ZnO: B, ZnO: Cd, InO, InSnO, ITO, SnO ₂ , SnO: F, RuO ₂ , IrO ₂ , or Cu ₂ O. Any one of them can be included. The second electrode 130 may include a charge compensator. The charge compensator may be a halogen element or a group 6 element. For example, the second electrode 130 may include any one of fluorine F, chlorine Cl, bromine Br, iodo I, oxygen O, sulfur S, selenium Se, and tellurium Te. The charge compensator can increase the conductivity of the second electrode 130.

The alkali metal-containing film 140 can be formed on the glass substrate 150 coated with the antireflection film 160. The alkali metal-containing film 140 may be in direct contact with the second electrode 130. The second electrode 140 may be disposed between the alkali metal-containing film 140 and the photoelectric conversion element 120. The alkali metal-containing film 140 may include an alkali metal. For example, the alkali metal can be sodium Na. The amount of the alkali metal compound in the alkali metal-containing film 140 may be 5 to 20 wt%. The alkali metal may be present in the alkali metal-containing film 140 in a form combined with oxygen O, boron B, hydrogen H, or fluorine F. When the alkali metal is sodium Na, the alkali metal-containing film 140 includes Al ₂ O ₃ , TiO ₂ , AlTiO, SiO ₂ , Si ₂ N ₄ , SiON, ZnO, ZnS, ZnSe, ZrO ₂ , HfO ₂ , MgO, CuO, or _Ta 2 _{O 5} wherein the alkali metal _{is NaF} to a thin film containing at least any one among the thin _{film, Na 2 O, NaAlO 2,} Na 2 O-Al 2 O 3 -nSiO 2 (n is an integer ), NaBO ₂ , Na ₂ B ₄ O ₇ , NaBH ₄ , Na ₂ C ₂ , NaBH ₄ , Na ₂ O ₂ , Na ₂ Si ₂ O ₅ , Na ₂ SiO ₃ , or Na ₄ SiO _4. Can exist in one form. Unlike this, the alkali metal-containing film 140 includes NaF, Na ₂ O, NaAlO ₂ , Na ₂ O—Al ₂ O ₃ —nSiO ₂ (n is an integer), NaBO ₂ , Na ₂ B ₄ O ₇ , NaBH. ₄ , Na ₂ C ₂ , NaBH ₄ , Na ₂ O ₂ , Na ₂ Si ₂ O ₅ , Na ₂ SiO ₃ , or Na ₄ SiO ₄ , a state of a substance manufactured using at least one of them as a precursor It can be. The conductivity of the alkali metal-containing layer 140 may be adjusted depending on whether or not electrical connection is necessary. The alkali metal-containing layer 140 may be formed by using a solution precursor, such as a sol-gel method, a spin-coating method, an imprinting method, a spray method, or a dipping method. Or can be formed using any one of screen printing methods. In contrast, the alkali metal-containing layer 140 may be formed using any one of a sputter method, an evaporation method, and a chemical vapor deposition method.

  In one embodiment, the alkali metal-containing film 140 may include nanoparticles in which one particle is isolated from each other. In one embodiment, the alkali metal-containing film 140 may be supplied in a thin film form.

  The refractive index of the alkali metal-containing film 140 may be larger than the refractive index of the glass substrate 150 and smaller than the refractive index of the second electrode 130. The refractive index of the alkali metal-containing film 140 may be a square root of multiplication of the refractive index of the glass substrate 150 and the refractive index of the second electrode 130. The alkali metal-containing layer 140 may serve as an anti-reflection layer that reduces reflection of incident light. The alkali metal in the alkali metal-containing film 140 can diffuse into the photoelectric conversion element 120 through the second electrode 130. The alkali metal diffused in the photoelectric conversion element 120 can remove defects in the photoelectric conversion element 120 and increase the photoelectric conversion efficiency of the photoelectric conversion element 120. Therefore, a solar cell optimized for high efficiency can be provided. Alkali metal is diffused into the photoelectric conversion element 120 to passivate defects of the photoelectric conversion element 120 and increase the photoelectric conversion efficiency of the photoelectric conversion element 120, thereby providing a high-efficiency solar cell. Can be provided. The glass substrate 150 may be a sodalime glass substrate. In contrast, the glass substrate 150 may be a glass substrate that does not contain sodium Na.

  The antireflection film 160 may include an incident surface on which light is incident from the light source LS. The light source LS may be the sun. Light incident through the antireflection film 160 may enter the photoelectric conversion element 120 through the antireflection film 160, the glass substrate 150, the alkali metal-containing film 140, and the second electrode 130. The antireflection film 160 can minimize the light incident from the light source LS from being reflected on the surface of the glass substrate 150. The antireflection film 160 is made of aluminum titanium oxide, silicon titanium oxide, aluminum zirconium oxide, zirconium titanium oxide, hafnium titanium oxide, zirconium oxide, titanium oxide, magnesium fluoride, magnesium oxide, hafnium oxide. And at least one of aluminum oxide, silicon oxide, and silicon nitride oxide.

  A modified embodiment of the photoelectric conversion element 120 according to the first embodiment of the present invention will be described. 5A and 5B are diagrams for explaining a modified embodiment of the photoelectric conversion element according to the first embodiment of the present invention.

  Referring to FIG. 5A, the photoelectric conversion element 121 may have a multi-junction structure including a plurality of stacked PIN diodes 510, 520, and 530. The first PIN diode 510 includes a first conductive type first semiconductor layer 512, an intrinsic second semiconductor layer 514 on the first semiconductor layer 512, and a second conductive type on the second semiconductor layer 514. A third semiconductor layer 516 can be included. A second PIN diode 520 may be disposed on the third semiconductor layer 516 of the first PIN diode 510. The second PIN diode 520 includes a first conductive type fourth semiconductor layer 522, an intrinsic fifth semiconductor layer 524, and a second conductive type sixth semiconductor layer, which are sequentially stacked on the third semiconductor layer 516. 526 may be included. A third PIN diode may be disposed on the sixth semiconductor layer 526 of the second PIN diode 520. The third PIN diode includes a first conductive type seventh semiconductor layer 532, an intrinsic eighth semiconductor layer 534, and a second conductive type ninth semiconductor layer 536, which are sequentially stacked on the sixth semiconductor layer 526. Can be included. The diodes 510, 520, and 530 may include two type semiconductor layers such as the first conductive type semiconductor layer and the second conductive type semiconductor layer. That is, the diodes 510, 520, and 530 may be PN diodes. Although three PIN diodes 510, 520, and 530 are illustrated in the drawing, the photoelectric conversion element 121 may include two or four or more PIN diodes.

  Referring to FIG. 5B, the photoelectric conversion element 123 may have a HIT (Heter Junction With Intrinsic Thin Layer) structure in which a single crystal silicon layer and an amorphous silicon layer are mixed. The photoelectric conversion element 123 includes a first conductive type first amorphous silicon layer 612, an intrinsic second amorphous silicon layer 614, a first conductive type single crystal silicon layer 620, an intrinsic state, which are sequentially stacked. The third amorphous silicon layer 616 and the fourth conductivity type fourth amorphous silicon layer 618 may be included. The first conductivity type may be an N type. The amorphous silicon layers 612, 614, 616, and 618 may be thinner than the single crystal silicon layer 620.

  A solar cell according to a modified embodiment of the first embodiment of the present invention will be described. FIG. 1B is a view for explaining a solar cell according to a modified embodiment of the first embodiment of the present invention.

  Referring to FIG. 1B, the first electrode 110 and the second electrode 130 described with reference to FIG. 1A may be provided. Any one of the photoelectric conversion elements 120, 121, and 123 described with reference to FIGS. 1A, 5A, and 5B may be provided. The second electrode 130 may be disposed on the glass substrate 150. The second electrode 130 may be interposed between the glass substrate 150 and the photoelectric conversion element 120. An antireflection film 160 may be disposed on the glass substrate 150. The glass substrate 150 may be interposed between the second electrode 130 and the antireflection film 160. The glass substrate 150 and the antireflection film 160 may include the same material as the glass substrate 150 and the antireflection film 160 described with reference to FIG. 1A.

  The first electrode 110 may include a first surface that contacts the photoelectric conversion element 120 and a second surface that faces the first surface. An alkali metal-containing film 140 may be disposed on the second surface of the first electrode 110. The alkali metal-containing film 140 may cover the second surface of the first electrode 110. The first electrode 110 may be disposed between the alkali metal-containing film 140 and the photoelectric conversion element 120. The alkali metal-containing film 140 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A. The alkali metal contained in the alkali metal-containing film 140 may be diffused into the photoelectric conversion element 120 through the first electrode 110.

  A solar cell according to another modified embodiment of the first embodiment of the present invention will be described. FIG. 1C is a view for explaining a solar cell according to another modified embodiment of the first embodiment of the present invention.

  Referring to FIG. 1C, the second electrode 130, the glass substrate 150, and the antireflection film 160 described with reference to FIG. 1B may be provided. Any one of the photoelectric conversion elements 120, 121, and 123 described with reference to FIGS. 1A, 5A, and 5B may be provided. The photoelectric conversion element 120 may include a first surface and a second surface facing the first surface. The second surface of the photoelectric conversion element 120 may be in contact with the second electrode 130. The first electrode 110 may be disposed on the first surface of the photoelectric conversion element 120. An alkali metal-containing film 140 may be interposed between the first electrode 110 and the photoelectric conversion element 120. The alkali metal-containing layer 140 may include a conductive material. The alkali metal-containing film 140 may electrically connect the first surface of the photoelectric conversion element 120 and the first electrode 110. The alkali metal-containing film 140 may serve as a reflective film that reflects light penetrating the photoelectric conversion element 120. The light reflected by the alkali metal-containing film 140 may be incident on the photoelectric conversion element 120 again. The alkali metal-containing film 140 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A.

  A solar cell according to another variant embodiment of the first embodiment of the invention will be described. FIG. 1D is a view for explaining a solar cell according to another modified embodiment of the first embodiment of the present invention.

  Referring to FIG. 1D, the second electrode 130, the alkali metal-containing film 140, the glass substrate 150, and the antireflection film 160 described with reference to FIG. 1A may be provided. Any one of the photoelectric conversion elements 120, 121, and 123 described with reference to FIGS. 1A, 5A, and 5B may be provided.

  The photoelectric conversion element 120 may include a first surface and a second surface facing the first surface. The second surface of the photoelectric conversion element 120 may be in contact with the second electrode 130. The first electrode 110 may be disposed on the first surface of the photoelectric conversion element 120. A first additional alkali metal-containing film 142 may be interposed between the first electrode 110 and the photoelectric conversion element 120. The first additional alkali metal-containing film 142 may be the alkali metal-containing film 140 described with reference to FIG. 1C.

  The first electrode 110 may include a first surface that contacts the first additional alkali metal-containing film 142 and a second surface that faces the first surface. A second additional alkali metal-containing film 144 may be disposed on the second surface of the first electrode 110. The first electrode 110 may be disposed between the second additional alkali metal-containing film 144 and the first additional alkali metal-containing film 142. The second additional alkali metal-containing film 144 may include the same material as the alkali metal-containing film 140.

  A solar cell according to a second embodiment of the present invention will be described. FIG. 2A is a view for explaining a solar cell according to a second embodiment of the present invention.

  Referring to FIG. 2A, a first electrode 210, a photoelectric conversion element 220, and a second electrode 230 are sequentially stacked on a substrate 250. The photoelectric conversion element 220 may be any one of the photoelectric conversion elements 120, 121, and 123 described with reference to FIGS. 1A, 5A, and 5B. The first electrode 210 and the second electrode 230 may be the first electrode 110 and the second electrode 130 described with reference to FIG. 1A.

  The first electrode 210 may have a first surface that contacts the photoelectric conversion element 220 and a second surface that faces the first surface. The substrate 250 may be in direct contact with the second surface of the first electrode 210. The substrate 250 may be the same as the glass substrate 150 described with reference to FIG. 1A. In contrast, the substrate 250 may be an opaque substrate. For example, the substrate 250 may be any one of a stainless steel, a copper, a plastic, a ceramic substrate, a flexible polymer film, or a flexible metal film.

  An alkali metal-containing layer 240 may be disposed on the second electrode 230. The alkali metal-containing film 240 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A. The alkali metal-containing film 240 may include an incident surface on which light is incident from the light source LS. The refractive index of the alkali metal-containing film 240 may be smaller than the refractive index of the second electrode 230. The alkali metal-containing film 240 can minimize reflection of light incident from the light source LS.

  A metal grid 246 may be disposed through the alkali metal-containing layer 240 to be in contact with the second electrode 230. The metal grid 246 may protrude from the alkali metal-containing film 240. The metal lattice 246 includes at least one of silver Ag, gold Au, platinum Pt, nickel Ni, copper Cu, carbon C, chromium Cr, aluminum Al, titanium Ti, molybdenum Mo, and tungsten W. Can do. The conductivity of the metal grid 246 may be higher than the conductivity of the second electrode 230. Due to the low resistance of the metal grid 246, a small amount of carriers formed in the photoelectric conversion element 220 are consumed by the light source LS, collected by the second electrode 230, and transmitted to the DC or AC load element. After the alkali metal-containing layer 240 is formed on the second electrode 230, the metal lattice 246 may be formed. In this case, after the metal grid 246 is formed, the metal in the metal grid 246 is diffused into the alkali metal-containing film 240 through a heat treatment, and the second electrode 230 and the metal grid 246 can be electrically connected. .

  A metal grid according to a second embodiment of the present invention will be described. FIG. 6A is a plan view for explaining a metal grid according to a second embodiment of the present invention. 2A is a cross-sectional view taken along the line I-I 'of FIG. 6A.

  Referring to FIGS. 2A and 6A, the metal grid 246 may be extended in a first direction parallel to the second surface of the photoelectric conversion element 220. The metal grid 246 may be extended in a second direction that intersects the first direction in parallel with the second surface of the photoelectric conversion element 220. The second direction may intersect the first direction at a right angle. On the other hand, the metal grid 246 may be composed of a plurality of conductive lines extending in the first direction.

  A metal grid according to a variant embodiment of the second embodiment of the invention will be described. FIG. 6B is a perspective view for explaining a metal grid according to a modified embodiment of the second embodiment of the present invention.

  Referring to FIG. 6B, the metal grid 246 is interposed between the alkali metal-containing film 240 and the second electrode 230, and the metal grid 246 is connected to the second surface of the photoelectric conversion element 220. It can be extended in a parallel first direction. The metal grid 246 may be extended in a second direction that intersects the first direction in parallel with the second surface of the photoelectric conversion element 220. The second direction may intersect the first direction at a right angle. In this case, the metal grid 246 may be formed on the second electrode 230 and then the alkali metal-containing film 240 may be formed. On the other hand, the metal grid 246 may be composed of a plurality of conductive lines extending in the first direction.

  A solar cell according to a modified embodiment of the second embodiment of the present invention will be described. FIG. 2B is a view for explaining a solar cell according to a modified embodiment of the second embodiment of the present invention.

  Referring to FIG. 2B, the photoelectric conversion element 220, the second electrode 230, the alkali metal-containing film 240, and the metal lattice 246 described with reference to FIG. 2A may be provided. The photoelectric conversion element 220 may include a first surface and a second surface facing the first surface. The second surface of the photoelectric conversion element 220 may be in contact with the second electrode 230. The first electrode 210 may be disposed on the first surface of the photoelectric conversion element 220. The first electrode 210 may include the same material as the first electrode 210 described with reference to FIG. 2A.

  An additional alkali metal-containing film 242 may be interposed between the first electrode 210 and the photoelectric conversion element 220. The first electrode 210 may have a first surface that contacts the additional alkali metal-containing film 242 and a second surface that faces the first surface. A substrate 250 may be disposed on the second surface of the first electrode 210. The substrate 250 may be the substrate 250 described with reference to FIG. 2A.

  The additional alkali metal-containing film 242 may include a conductive material. The additional alkali metal-containing film 242 may electrically connect the first surface of the photoelectric conversion element 220 and the first electrode 210. The additional alkali metal-containing film 242 may serve as a reflective film that reflects light penetrating the photoelectric conversion element 220. The light reflected by the additional alkali metal-containing film 242 may be incident on the photoelectric conversion element 220 again. The additional alkali metal-containing film 242 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A.

  A solar cell according to another modified embodiment of the second embodiment of the present invention will be described. FIG. 2C is a view for explaining a solar cell according to another modified embodiment of the second embodiment of the present invention.

  Referring to FIG. 2C, the substrate 250, the first electrode 210, the additional alkali metal-containing film 242, the photoelectric conversion element 220, the second electrode 230, and the alkali metal-containing film 240 described with reference to FIG. 2B may be provided. . The metal grid 246 described with reference to FIGS. 2A and 6A may be provided.

  An antireflection film 260 may be provided on the alkali metal-containing film 240. The antireflection film 260 may cover the alkali metal-containing film 240. The alkali metal-containing film 240 may be disposed between the antireflection film 260 and the second electrode 230. The antireflection layer 260 may include the same material as the antireflection layer 260 described with reference to FIG. 1A. The antireflection film 260 may include an incident surface on which light is incident from the light source LS. The antireflection film 260 can minimize reflection of light incident from the light source LS.

  The metal grid 246 may be in contact with the second electrode 240 through the alkali metal-containing film 240 and the antireflection film 260. In contrast, as described with reference to FIG. 6B, the metal grid 246 may be provided between the second electrode 230 and the alkali metal-containing film 240.

  A solar cell according to a third embodiment of the present invention will be described. FIG. 3A is a view for explaining a solar cell according to a third embodiment of the present invention. The solar cell according to the third embodiment of the present invention may be a transparent solar cell.

Referring to FIG. 3A, a first electrode 310, a photoelectric conversion element 320, and a second electrode 330 that are sequentially stacked may be provided. The first electrode 310 and the second electrode 330 may include a transparent and conductive material. For example, the first electrode 310 and the second electrode 330 may be ZnO: Al, ZnO: Ga, ZnO: B, ZnO: Cd, InSnO, ITO, SnO ₂ , SnO: F, RuO ₂ , IrO ₂ , or Any one of Cu ₂ O can be included. The photoelectric conversion element 320 may be any one of the photoelectric conversion elements 120, 121, and 123 described with reference to FIGS. 1A, 5A, and 5B.

  The alkali metal-containing film 340 may be formed on the glass substrate 350, and the opposite surface of the glass substrate 350 may be coated with the antireflection film 360. The alkali metal-containing film 340 may be disposed between the glass substrate 350 and the second electrode 330. The glass substrate 350 may be disposed between the antireflection film 360 and the alkali metal-containing film 340. The alkali metal-containing film 340, the glass substrate 350, and the antireflection film 360 may be the alkali metal-containing film 140, the glass substrate 150, and the antireflection film 160 described with reference to FIG. 1A, respectively.

  The first electrode 310 may include a first surface that contacts the photoelectric conversion element 320 and a second surface that faces the first surface. A metal grid 316 may be disposed on the second surface of the first electrode 310. The metal grid 316 may protrude from the second surface of the first electrode 310. The metal grid 316 includes a first direction parallel to the second surface of the photoelectric conversion element 320 as in the metal grid 246 described with reference to FIG. 6A, and the second surface of the photoelectric conversion element 320. It may extend in a second direction that is parallel to the first direction. The second direction may intersect the first direction at a right angle. On the other hand, the metal grid 316 may be composed of a plurality of conductive lines extending in the first direction.

  The metal grid 316 may include the same material as the metal grid 246 described with reference to FIG. 2A. The conductivity of the metal grid 316 may be higher than the conductivity of the first electrode 310.

  Due to the high conductivity of the metal grid 316, a small amount of carriers formed in the photoelectric conversion element 320 are consumed by the light source LS, collected by the first electrode 310, and transmitted to a DC or AC load element.

  A solar cell according to a modified embodiment of the third embodiment of the present invention will be described. FIG. 3B is a view for explaining a solar cell according to a modified embodiment of the third embodiment of the present invention.

  Referring to FIG. 3B, the first electrode 310, the photoelectric conversion element 320, and the second electrode 330 described with reference to FIG. 3A may be provided. The first electrode 310 may include a charge compensator. The charge compensator may be a halogen element or a group 6 element. For example, the second electrode 130 may include any one of fluorine F, chlorine Cl, bromine Br, iodo I, oxygen O, sulfur S, selenium Se, and tellurium Te. The charge compensator can increase the conductivity of the first electrode 310.

  A glass substrate 350 may be disposed on the second electrode 330. The second electrode 330 may be disposed between the glass substrate 350 and the photoelectric conversion element 320. An anti-reflection layer 360 may be disposed on the glass substrate 350. The glass substrate 350 may be disposed between the antireflection film 360 and the second electrode 330. The glass substrate 350 and the antireflection film 360 may each include the same material as the glass substrate 350 and the antireflection film 360 described with reference to FIG. 3A.

  The first electrode 310 may include a first surface that contacts the photoelectric conversion element 320 and a second surface that faces the first surface. An alkali metal-containing film 342 may be disposed on the second surface of the first electrode 310. The first electrode 310 may be disposed between the alkali metal-containing film 342 and the photoelectric conversion element 320. The alkali metal-containing film 342 may have a higher reflectance for incident light in the first wavelength band than in the second wavelength band. The first wavelength band and the second wavelength band may be different wavelength bands. For example, the first wavelength band may include infrared light or ultraviolet light, and the second wavelength band may include visible light. The light in the first wavelength band reflected by the alkali metal-containing film 342 enters the photoelectric conversion element 320, and is reflected by the alkali metal-containing film 342 and re-enters the photoelectric conversion element 320. Carriers (for example, holes or electrons) can be generated in the inside.

  The first wavelength band and the second wavelength band may be adjusted by the optical thickness of the alkali metal-containing film 342. The optical thickness is a product of the refractive index of the medium and the physical thickness of the medium. The refractive index of the alkali metal-containing film 342 can be changed according to the composition ratio of the substances constituting the alkali metal-containing film 342. The alkali metal-containing film 342 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A.

  A metal grid 316 may be disposed through the alkali metal-containing film 342 and in contact with the first electrode 310. The metal grid 316 includes a first direction parallel to the second surface of the photoelectric conversion element 320 as in the metal grid 246 described with reference to FIG. 6A, and the second surface of the photoelectric conversion element 320. It may extend in a second direction that is parallel to the first direction. The second direction may intersect the first direction at a right angle. On the other hand, the metal grid 316 may be composed of a plurality of conductive lines extending in the first direction. The metal grid 316 may include the same material as the metal grid 316 described with reference to FIG. 3A. The metal grid 316 may protrude from the alkali metal-containing film 342 and the first electrode 310. In contrast, the metal lattice 316 may be interposed between the alkali metal-containing film 342 and the first electrode 310 as described with reference to FIG. 6B.

  A solar cell according to another modified embodiment of the third embodiment of the present invention will be described. FIG. 3C is a view for explaining a solar cell according to another modified embodiment of the third embodiment of the present invention.

  Referring to FIG. 3C, the first electrode 310, the photoelectric conversion element 320, the second electrode 330, the alkali metal-containing film 340, the glass substrate 350, the antireflection film 360, and the metal lattice 316 described with reference to FIG. Can be provided. The first electrode 310 may include a first surface that contacts the photoelectric conversion element 320 and a second surface that faces the first surface. An additional alkali metal-containing film 342 may be disposed on the second surface of the first electrode 310. The first electrode 310 may be disposed between the additional alkali metal-containing film 342 and the photoelectric conversion element 320. The additional alkali metal-containing film 342 may be the alkali metal-containing film 340 described with reference to FIG. 3B. The metal grid 316 may be in contact with the first electrode 310 through the additional alkali metal-containing layer 342.

  A solar cell according to a fourth embodiment of the present invention will be described. FIG. 4A is a view for explaining a solar cell according to a fourth embodiment of the present invention.

Referring to FIG. 4A, a photoelectric conversion element 420 may be provided. The photoelectric conversion element 420 generates carriers (for example, holes or electrons) by incident sunlight. The photoelectric conversion element 420 may include a first surface and a second surface opposite to the first surface. The photoelectric conversion element 420 may include a first conductive type semiconductor layer and a second conductive type semiconductor layer on the first conductive type semiconductor layer. The first conductive semiconductor layer and the second conductive semiconductor layer may be in contact with each other. The first conductivity type and the second conductivity type may be different conductivity types. The first surface and the second surface of the photoelectric conversion element 420 may be surfaces included in semiconductor layers having different conductivity types. For example, the first surface of the photoelectric conversion element 420 is a surface included in an N-type semiconductor layer, and the second surface of the photoelectric conversion element 420 is a surface included in a P-type semiconductor layer. (Surface). The photoelectric conversion element 420 is one of CdS, ZnO, ZnS, CuZnSnS, CuZnSnSe, Cu ₂ O, GaAs, GaInAs, GaInAlAs, or InP, which is Si, SiGe, CuInSe, CuInS, CuInGaSe, or CuInGaS. Can be included. The photoelectric conversion element 420 may include an organic semiconductor material.

  The first surface of the photoelectric conversion element 420 may be connected to the first electrode 410. The first electrode 410 may be the first electrode 110 described with reference to FIG. 1A.

  An alkali metal-containing film 440 may be disposed on the first surface of the photoelectric conversion element 420. The alkali metal-containing film 440 can be directly connected to the first surface of the photoelectric conversion element 420. The photoelectric conversion element 420 may be disposed between the alkali metal-containing film 440 and the first electrode 410. The alkali metal-containing film 440 may function as an antireflection film that reduces reflection of light incident from the light source LS. The alkali metal-containing film 440 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A. Alkali metal contained in the alkali metal-containing film 440 is directly diffused into the photoelectric conversion element 420, and the photoelectric conversion efficiency of the photoelectric conversion element 420 is increased. The portion of the photoelectric conversion element 420 connected to the alkali metal-containing film 440 may be an amorphous, microcrystalline, or polycrystalline film formed using a thin film deposition method.

  The second surface of the photoelectric conversion element 420 may be connected to the second electrode 430. The second electrode 430 may be in the form of a metal grid that is in contact with the photoelectric conversion element 420. The second electrode 430 may be in direct contact with the photoelectric conversion element 420 through the alkali metal-containing film 440. The second electrode 430 may protrude from the alkali metal-containing film 440. The second electrode 430 includes a first direction parallel to the second surface of the photoelectric conversion element 420 and the second surface of the photoelectric conversion element 420 as in the metal lattice 246 described with reference to FIG. And extend in a second direction that intersects the first direction. The second direction may intersect the first direction at a right angle. On the other hand, the second electrode 430 may be composed of a plurality of conductive lines extending in the first direction.

  The second electrode 430 may include the same material as the metal grid 246 described with reference to FIG. 2A.

  A solar cell according to a modified embodiment of the fourth embodiment of the present invention will be described. FIG. 4B is a view for explaining a solar cell according to a modified embodiment of the fourth embodiment of the present invention.

  Referring to FIG. 4B, the first electrode 410, the photoelectric conversion element 420, the second electrode 430, and the alkali metal-containing film 440 described with reference to FIG. 4A are provided. The first electrode 410 may include a first surface that contacts the photoelectric conversion element 420 and a second surface that faces the first surface. An additional alkali metal-containing film 442 may be disposed on the second surface of the first electrode 410. The first electrode 410 may be disposed between the additional alkali metal-containing film 442 and the photoelectric conversion element 420. The additional alkali metal-containing film 442 may include the same material as the alkali metal-containing film 140 described with reference to FIG. 1A.

  The alkali metal in the alkali metal-containing film 440 can be directly diffused into the photoelectric conversion element 420, and the alkali metal in the additional alkali metal-containing film 442 is diffused into the photoelectric conversion element 420 through the first electrode 410. can do.

110, 210, 310, 410 First electrode 120, 220, 320, 420 Photoelectric conversion element 130, 230, 330, 430 Second electrode 140, 240, 340, 440 Alkali metal-containing film 150, 250, 350, 450 Glass substrate 160, 260, 360, 460 Antireflection film 246, 316 Metal lattice

Claims (19)

A photoelectric conversion element including a first surface and a second surface facing the first surface;
A first electrode connected to the first surface of the photoelectric conversion element;
A second electrode connected to the second surface of the photoelectric conversion element;
An alkali metal-containing film in contact with any one of the first electrode and the second electrode;
The photoelectric conversion element is a solar cell made of CuInGaSe. The alkali metal-containing film is disposed on the second electrode and functions as an antireflection film,
The solar cell according to claim 1, wherein the second electrode is interposed between the alkali metal-containing film and the photoelectric conversion element. A glass substrate disposed on the alkali metal-containing film;
An antireflection film disposed on the glass substrate,
The alkali metal-containing film is disposed between the glass substrate and the second electrode,
The glass substrate is disposed between the antireflection film and the alkali metal-containing film,
The solar cell according to claim 2, wherein a refractive index of the alkali metal-containing film is larger than a refractive index of the glass substrate and smaller than a refractive index of the second electrode. The first electrode includes a first surface that contacts the photoelectric conversion element, and a second surface that faces the first surface,
A substrate covering the second surface of the first electrode;
The solar cell according to claim 2, further comprising: a metal grid that penetrates through the alkali metal-containing film and contacts the second electrode. Further comprising an antireflection film disposed on the alkali metal-containing film,
The solar cell according to claim 4, wherein the metal grid further penetrates the antireflection film. The first electrode includes a first surface that contacts the photoelectric conversion element, and a second surface that faces the first surface,
The solar cell according to claim 1, wherein the alkali metal-containing film covers the second surface of the first electrode. A glass substrate disposed on the second electrode;
An antireflection film disposed on the glass substrate,
The solar cell according to claim 6, wherein the glass substrate is disposed between the second electrode and the antireflection film.   The solar cell according to claim 7, further comprising a metal lattice that penetrates through the alkali metal-containing film and contacts the first electrode. The alkali metal-containing film has a higher reflectance with respect to the first wavelength band of incident light than a reflectance with respect to the second wavelength band,
The solar cell according to claim 6, wherein the first wavelength band and the second wavelength band are different.   The solar cell according to claim 9, wherein the second wavelength band includes visible light. Further comprising an additional alkali metal-containing film disposed on the second electrode;
The solar cell according to claim 6, wherein the second electrode is disposed between the additional alkali metal-containing film and the photoelectric conversion element. The alkali metal-containing film covers the upper surface of the photoelectric conversion element, performs the function of an antireflection film,
The solar cell according to claim 1, wherein the second electrode is a metal grid that penetrates the alkali metal-containing film and is connected to the photoelectric conversion element. The first electrode includes a first surface that contacts the photoelectric conversion element, and a second surface that faces the first surface,
The solar cell according to claim 12, further comprising an additional alkali metal-containing film covering the second surface of the first electrode.   2. The sun according to claim 1, wherein the alkali metal-containing film is disposed between the first surface of the photoelectric conversion element and the first electrode, and electrically connects the photoelectric conversion element and the first electrode. battery.   The solar cell according to claim 1, wherein the electrode in contact with the alkali metal-containing film contains a halogen element and a Group 6 element.   The solar cell according to claim 1, wherein the alkali metal in the alkali metal-containing film is bonded to oxygen, boron, hydrogen, or fluorine. Wherein the alkali metal-containing _{film, NaF, NaO, NaAlO 2,} Na 2 O-Al 2 O 3 -nSiO 2 (n is an _{integer), NaBO 2, Na 2 B} 4 O 7, NaBH 4, Na 2 C 2, _2. The solar cell according to claim 1, comprising an alkali metal which is any one in a compound state of NaBH ₄ , Na ₂ O ₂ , Na ₂ Si ₂ O ₅ , Na ₂ SiO ₃ , and Na ₄ SiO ₄ .   The solar cell according to claim 1, wherein the amount of alkali metal in the alkali metal-containing film is 5 to 20 wt%. 2. The solar cell according to claim 1, wherein a part of the alkali metal in the alkali metal-containing film penetrates through an electrode in contact with the alkali metal-containing film and is diffused into the photoelectric conversion element.