TWI624077B - Method of manufacturing buffer layer for solar cell - Google Patents

Abstract

A method of making a buffer layer for a solar cell, comprising providing a precursor solution comprising a solvent, a primary metal element, and a Group VIA element. The primary metal element is selected from the group consisting of zinc, cadmium, indium, and combinations thereof. Group VIA elements are selected from the group consisting of oxygen, sulfur, selenium, and combinations thereof. The laminate structure is contacted with the precursor solution to form a deposited layer on the laminate structure. The deposited layer is heat-treated under an atmosphere to form a buffer layer in which the atmosphere contains a Group VIA element, and the heat treatment temperature is from 50 ° C to 300 ° C.

Description

Method for manufacturing buffer layer of solar cell

The present invention relates to a method of manufacturing a buffer layer for a solar cell.

In recent years, due to global climate change, environmental pollution problems and the shortage of resources, the solar photovoltaic industry has been booming under the warning of high environmental awareness and energy crisis. Among various solar cells, copper indium gallium selenide solar cells (Cu(In,Ga)Se ₂ , CIGS) are highly valued because of their high conversion efficiency, good stability, low material cost, and the ability to be made into a thin film. .

In general, a copper indium gallium selenide solar cell comprises a substrate, a back electrode, a light absorbing layer, a buffer layer, a transparent window layer and a front electrode stacked in sequence. Most of the current buffer layers are made of cadmium sulfide or zinc sulfide, but they have not significantly improved the performance of copper indium gallium selenide solar cells.

The object of the present invention is to provide a method for manufacturing a buffer layer of a solar cell, which can effectively improve the performance of the solar cell, for example, an open circuit voltage (V _oc ), a short circuit current (I _sc ), a fill factor (FF), and photoelectric conversion. effectiveness.

The method for producing a buffer layer for a solar cell provided by the present invention comprises providing a precursor solution comprising a solvent, a main metal element, and a Group VIA element. The primary metal element is selected from the group consisting of zinc, cadmium, indium, and combinations thereof. Group VIA elements are selected from the group consisting of oxygen, sulfur, selenium, and combinations thereof. The laminate structure is contacted with the precursor solution to form a deposited layer on the laminate structure. The deposited layer is heat-treated under an atmosphere to form a buffer layer in which the atmosphere contains a Group VIA element, and the heat treatment temperature is from 50 ° C to 300 ° C.

According to an embodiment of the invention, the Group VIA element comprises sulfur, selenium, oxygen or a combination thereof.

According to an embodiment of the invention, the atmosphere comprises hydrogen sulfide, hydrogen selenide, sulfur vapor, selenium vapor or a combination thereof.

According to an embodiment of the invention, the atmosphere further comprises hydrogen, an inert gas or a combination thereof.

According to an embodiment of the invention, the inert gas is nitrogen, argon or a combination thereof.

According to an embodiment of the invention, the heat treatment time is from 10 minutes to 8 hours.

According to an embodiment of the invention, the precursor solution further comprises hydroxide ions.

According to an embodiment of the invention, the laminated structure comprises a substrate, the back electrode is on the substrate, and the light absorbing layer is on the back electrode, and the step of contacting the laminated structure with the precursor solution comprises contacting the light absorbing layer of the laminated structure with the precursor solution. To form a deposited layer on the light absorbing layer.

According to an embodiment of the invention, the precursor solution further comprises a doping element selected from the group consisting of Group IA, titanium, lead, tin, nickel, ruthenium, osmium, and combinations thereof.

According to an embodiment of the invention, the precursor solution further comprises an acid or a base.

The embodiments of the present invention are disclosed in the following drawings, and for the purpose of illustration However, it should be understood that these practical details are not intended to limit the invention. That is, in some embodiments of the invention, these practical details are not necessary. In addition, some of the conventional structures and elements are shown in the drawings in a simplified manner in the drawings.

According to the prior art, the current buffer layer fails to significantly improve the performance of the copper indium gallium selenide solar cell. Accordingly, the present invention provides a method of fabricating a buffer layer for a solar cell that can effectively enhance the performance of the solar cell. Several embodiments of the method of manufacturing the buffer layer of the solar cell will be described in detail below.

First, a precursor solution is provided. The precursor solution contains a solvent, a main metal element, and a Group VIA element. The solvent may be water, alcohols, ketones, ethers, amines, bases, acids or a combination of the above. The above alcohols include methanol, ethanol, propanol, isopropanol, n-butanol, isoamyl alcohol or ethylene glycol; ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone; ethers include methyl ether, diethyl ether, A Ether, diphenyl ether, ethylene glycol methyl ether, ethylene glycol butyl ether or ethylene glycol ethyl ether; amines include ethylenediamine, dimethylformamide, triethanolamine or diethanolamine; alkalis include sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), urea (CON ₂ H ₄ ), ammonia (NH ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium hydrogencarbonate (NaHCO ₃ ) or the like a combination comprising acid (CH ₃ COOH), acetic acid (C ₂ H ₅ COOH), hydrochloric acid (HCl), nitric acid (HNO ₃ ), sulfuric acid (H ₂ SO ₄ ), carbonic acid (H ₂ CO ₃ ), and citric acid (C ₆ H ₈ O ₇ ) and combinations thereof. In an embodiment, the solvent comprises water.

The main metal element may be a compound containing a main metal element, such as an oxide containing a main metal element, a nitrate, a halide, an acetate, and a sulfate such as cadmium nitrate, cadmium chloride, cadmium acetate, cadmium sulfate, Cadmium iodide, zinc nitrate, zinc chloride, zinc acetate, zinc sulfate, zinc iodide, indium nitrate, indium chloride, indium acetate, indium iodide or indium sulfate. However, the selection of the compound containing a main metal element is not limited to the above-mentioned compounds, and any compound which can contain a main metal element cation is suitable for use in the present invention.

Group VIA elements are selected from the group consisting of oxygen, sulfur, selenium, and combinations thereof. The source of the Group VIA element may be a compound containing a Group VIA element such as thiourea (SC(NH ₂ ) ₂ ), thioacetamide, dimethyl disulfide (CH ₃ -SS-CH ₃ ), Allyl disulfide (H ₂ C=CH-CH ₂ S-SCH ₂ -CH=CH ₂ ), sulfur powder (S), selenium powder (Se), selenite (H ₂ SeO ₃ ), selenic acid (H ₂ SeO ₄ ), methyl selenol (CH ₄ Se), ethyl selenol (CH ₃ CH ₂ SeH), propenol (C ₃ H ₇ SeH), butenol (C ₄ H ₉ SeH), and the like. However, the selection of the compound containing a Group VIA element is not limited to the above-mentioned compounds, and any compound which can contain an anion of a Group VIA is suitable for use in the present invention.

In one embodiment, the precursor solution further comprises a doping element selected from the group consisting of Group IA, titanium, lead, tin, nickel, ruthenium, osmium, and combinations thereof. The above doping elements contribute to the performance of the solar cell. In one embodiment, the molar ratio of the doping element to the primary metal element is from 0.01:100 to 8:100.

In one embodiment, the precursor solution further comprises a base or an acid to adjust the pH of the precursor solution. In an embodiment, the precursor solution further comprises hydroxide ions.

In one embodiment, the precursor solution further comprises aqueous ammonia to adjust the pH of the precursor solution.

After the precursor solution is provided, the laminate structure is contacted with the precursor solution to form a deposited layer on the laminate structure. The precursor solution can be chemically bathed (CC) to grow a suitable deposited layer on the laminate structure. This chemical water bath deposition method can be carried out at room temperature to 99 ° C for a reaction time of 3 minutes to 8 hours. The thickness of the deposited layer can be controlled by controlling the deposition time. In one embodiment, the laminate structure includes a substrate, a back electrode, and a light absorbing layer, the back electrode is on the substrate, and the light absorbing layer is on the back electrode. Then, the light absorbing layer of the laminate structure is brought into contact with the precursor solution to form a deposited layer on the light absorbing layer.

For example, as shown in FIG. 1, the laminated structure includes the substrate 10, the back electrode 20, and the light absorbing layer 30. The light absorbing layer 30 is then brought into contact with the precursor solution to form a deposited layer (not shown) on the light absorbing layer 30. The substrate 10 can be a glass, a polymeric substrate, a metal substrate, or a transparent conductive layer. The back electrode 20 may be a molybdenum containing metal layer, for example, formed by sputtering. The light absorbing layer 30 is disposed above the back electrode 20 and functions as a P-type semiconductor layer. The light absorbing layer 30 may comprise a copper indium selenide compound, a copper indium sulfide compound, a copper indium gallium sulfide compound, a copper indium gallium sulfide selenium compound, a copper indium gallium selenide compound, a copper gallium selenium compound, a copper gallium sulfur compound, a copper zinc tin selenium compound. , copper zinc tin sulphur compound, copper zinc tin sulphide selenium compound, cadmium telluride or a combination thereof. The compound structure of the light absorbing layer 30 may be a chalcopyrite phase, a zinc tin ore phase, a zinc blende phase, a kersterite structure, or a combination thereof.

Then, the deposited layer is subjected to heat treatment under an atmosphere to form a buffer layer. For example, as shown in FIG. 1, the deposited layer on the light absorbing layer 30 is subjected to heat treatment to form the buffer layer 40. In particular, the buffer layer 40 is then heat treated in an atmosphere containing a Group VIA element. In one embodiment, the Group VIA element comprises sulfur, selenium, oxygen, or a combination thereof. In an embodiment, the heat treatment atmosphere comprises hydrogen sulfide, hydrogen selenide, sulfur vapor, selenium vapor, or a combination thereof. In one embodiment, the temperature of the heat treatment is from 50 ° C to 300 ° C. In one embodiment, the temperature of the heat treatment is from 120 ° C to 250 ° C. In one embodiment, the temperature of the heat treatment is from 100 ° C to 180 ° C. In one embodiment, the heat treatment time is from 10 minutes to 8 hours. In one embodiment, the heat treatment time is from 15 minutes to 1 hour. It can be seen from the following experimental examples and comparative examples that the heat treatment contributes to a significant increase in the open circuit voltage, short circuit current, fill factor, and conversion efficiency of the solar cell. It may be because the pores in the crystal structure of the deposited layer gradually disappear through the heat treatment, and a buffer layer having a dense and high coverage is formed, so that the photoelectric characteristics of the solar cell can be greatly improved.

In an embodiment, the atmosphere of the heat treatment may comprise an inert gas for use as a carrier gas. In an embodiment, the inert gas is nitrogen, argon or a combination thereof. In addition to assisting the flow of reactive Group VIA gases, inert gases can also regulate the proportion of Group VIA elements. In one embodiment, the inert gas has a molar ratio of from 0 to 0.99 in the total atmosphere.

After the heat treatment, the transparent window layer and the front electrode are sequentially formed on the buffer layer. For example, as shown in FIG. 1, the transparent window layer 50 and the front electrode 60 may be sequentially formed on the buffer layer 40. The transparent window layer 50 may be zinc oxide (ZnO), indium tin oxide (ITO), zinc oxide boron (BZO), zinc aluminum oxide (AZO), zinc gallium oxide (GZO), or a combination thereof. The transparent window layer material is not limited by the above materials, and only needs to have light transmissivity. The front electrode 60 is used to collect the current generated by the solar cell 1. The material of the front electrode 60 may be, for example, nickel or nickel aluminum alloy.

Experimental Example 1 Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, ammonia water, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to form soda lime glass/ Mo/CIGS/cadmium sulfide. This soda lime glass / Mo / CIGS / CdS samples were placed in high purity _{10% H 2 S / 90%} N 2 mixed gas atmosphere, heat treatment is carried out after ^{120 o C (post-annealing treatment} , PAT) 4 hours to obtain Soda lime glass/Mo/CIGS/cadmium sulfide (PAT).

Copper indium gallium selenide thin film solar cells were fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide (PAT)/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cells were analyzed by solar standard light source simulator. The experimental results show The open circuit voltage (Voc) was 0.580 V, the short circuit current (Jsc) was 31.64 mA/cm ² , the fill factor (FF) was 64.95%, and the photoelectric conversion efficiency was 11.92%.

In Comparative Example 1, Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, and ammonia is used, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to obtain soda lime glass/ Mo/CIGS/cadmium sulfide.

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The experiment showed that the open circuit voltage (Voc) The current is 0.562V, the short-circuit current (Jsc) is 31.24 mA/cm ² , the fill factor (FF) is 58.57%, and the photoelectric conversion efficiency is 10.29%. Compared with Comparative Example 1 which was not subjected to post-heat treatment, the post-heat treatment cadmium sulfide (PAT) film was applied to the copper indium gallium selenide thin film solar cell, and the open circuit voltage, short circuit current, fill factor and conversion efficiency were significantly increased.

Experimental Example 2 In the CuGa alloy and the metal is deposited by sputtering on the substrate, the precursor film was formed were stacked, and then the high-purity nitrogen gas mixture of hydrogen, for 0.5 hour to 550 ^o C and selenium vapor passed to A CIGS film is formed. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, ammonia water, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to form soda lime glass/ Mo/CIGS/cadmium sulfide. This soda lime glass / Mo / CIGS / CdS samples were placed in high purity _{10% H 2 S / 90%} N 2 mixed gas atmosphere, heat treatment is carried out after ^{200 o C (post-annealing treatment} , PAT) 0.5 hours to obtain Soda lime glass/Mo/CIGS/cadmium sulfide (PAT).

Copper indium gallium selenide thin film solar cells were fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide (PAT)/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cells were analyzed by solar standard light source simulator. The experimental results show The open circuit voltage (Voc) was 0.446 V, the short circuit current (Jsc) was 33.44 mA/cm ² , the fill factor (FF) was 60.36%, and the photoelectric conversion efficiency was 9.01%.

Comparative Example 2 In the CuGa alloy and the metal is deposited by sputtering on the substrate, the precursor film was formed were stacked, and then the high-purity nitrogen gas mixture of hydrogen, for 0.5 hour to 550 ^o C and selenium vapor passed to A CIGS film is formed. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, and ammonia is used, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to obtain soda lime glass/ Mo/CIGS/cadmium sulfide.

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The experiment showed that the open circuit voltage (Voc) The current is 0.441V, the short-circuit current (Jsc) is 33.40 mA/cm ² , the fill factor (FF) is 55.11%, and the photoelectric conversion efficiency is 8.12%. Compared with Comparative Example 2 which was not post-heat treated, the post-heat treatment cadmium sulfide (PAT) film was applied to the copper indium gallium selenide thin film solar cell, and the open circuit voltage, short circuit current, fill factor and conversion efficiency were significantly increased.

Experimental Example 3 Cu(NO ₃ ) ₂ , Ga(NO ₃ ) ₃ and In(NO ₃ ) _{3 were} dissolved in ethanol to prepare a solution, and after adding a binder and uniformly mixing, it became a precursor solution and was spin-coated. The cloth method applies the precursor solution to the glass substrate, heats and dries the solution, and then heats the selenium vapor to form a CIGS film. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, ammonia water, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to form soda lime glass/ Mo/CIGS/cadmium sulfide. This soda lime glass / Mo / CIGS / CdS samples were placed in high purity _{10% H 2 S / 90%} N 2 mixed gas atmosphere, heat treatment is carried out after ^{250 o C (post-annealing treatment} , PAT) 0.5 hours to obtain Soda lime glass/Mo/CIGS/cadmium sulfide (PAT).

Copper indium gallium selenide thin film solar cells were fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide (PAT)/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cells were analyzed by solar standard light source simulator. The experimental results show The open circuit voltage (Voc) was 0.460 V, the short circuit current (Jsc) was 32.82 mA/cm ² , the fill factor (FF) was 58.07%, and the photoelectric conversion efficiency was 8.77%.

In Comparative Example 3, Cu(NO ₃ ) ₂ , Ga(NO ₃ ) ₃ and In(NO ₃ ) _{3 were} dissolved in ethanol to prepare a solution, and after adding a binder and uniformly mixing, it became a precursor solution and was spin-coated. The cloth method applies the precursor solution to the glass substrate, heats and dries the solution, and then heats the selenium vapor to form a CIGS film. A cadmium sulfide film of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing cadmium sulfate, thiourea, and ammonia is used, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a cadmium sulfide film on soda lime glass/Mo/CIGS to obtain soda lime glass/ Mo/CIGS/cadmium sulfide.

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/cadmium sulfide/i-ZnO/ITO, and the copper indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The experiment showed that the open circuit voltage (Voc) ) is 0.422V, the short-circuit current (Jsc) is 32.43 mA/cm ² , the fill factor (FF) is 53.46%, and the photoelectric conversion efficiency is 7.32%. Compared with Comparative Example 2 which was not post-heat treated, the post-heat treatment cadmium sulfide (PAT) film was applied to the copper indium gallium selenide thin film solar cell, and the open circuit voltage, short circuit current, fill factor and conversion efficiency were significantly increased.

Experimental Example 4 Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A buffer layer of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing zinc sulfate, thiourea, ammonia water, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a zinc sulfide film on soda lime glass/Mo/CIGS to form soda lime glass/ Mo/CIGS/zinc sulfide. This soda lime glass / Mo / CIGS / ZnS sample was placed in a high purity 5% H2S / 90% N2 mixed atmosphere, heat to 180 ^o C for years after (post-annealing treatment, PAT) 1 hour to obtain soda Lime glass/Mo/CIGS/zinc sulfide (PAT).

The copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/zinc sulfide (PAT)/i-ZnO/ITO, and the solar indium gallium selenide thin film solar cell was analyzed by solar standard light source simulator. The experimental results show The open circuit voltage (Voc) was 0.433 V, the short circuit current (Jsc) was 32.81 mA/cm ² , the fill factor (FF) was 43.78%, and the photoelectric conversion efficiency was 6.21%.

In Comparative Example 4, Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A buffer layer of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing zinc sulfate, thiourea, ammonia water, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit a zinc sulfide film on soda lime glass/Mo/CIGS to obtain soda lime glass/ Mo/CIGS/zinc sulfide.

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/zinc sulfide/i-ZnO/ITO, and the solar indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The experiment showed that the open circuit voltage (Voc) The current is 0.341V, the short-circuit current (Jsc) is 30.56 mA/cm ² , the fill factor (FF) is 30.96%, and the photoelectric conversion efficiency is 3.23%. Compared with the comparative example 4 in the post-heating section, the open circuit voltage, short-circuit current, filling factor and conversion efficiency of the copper-indium-gallium-selenide thin film solar cell after the zinc oxide (PAT) film in the post-heating zone were significantly increased.

Experimental Example 5 Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A buffer layer of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing indium chloride, thioacetamide, acetic acid is used, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit an indium sulfide film on soda lime glass/Mo/CIGS to form Soda lime glass/Mo/CIGS/indium sulfide. This soda lime glass / Mo / CIGS / indium sulfide samples were placed in high purity 5% H2S / 90% N2 mixed atmosphere, to 220 ^o C after heat Lane (post-annealing treatment, PAT) 1 hour to obtain soda Lime glass/Mo/CIGS/indium sulfide (PAT).

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/indium sulfide (PAT)/i-ZnO/ITO, and the solar indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The open circuit voltage (Voc) was 0.435 V, the short circuit current (Jsc) was 32.83 mA/cm ² , the fill factor (FF) was 54.99%, and the photoelectric conversion efficiency was 7.85%.

In Comparative Example 5, Cu metal, In metal, Ga metal, and Se element were deposited on a substrate by a multi-evaporation method to form a CIGS film. A buffer layer of a copper indium gallium selenide (CIGS) solar cell was prepared by a chemical water bath deposition method. A precursor solution containing indium chloride, thioacetamide, acetic acid, and soda lime glass/Mo/CIGS is immersed in the precursor solution to deposit an indium sulfide film on the soda lime glass/Mo/CIGS, Obtained soda lime glass/Mo/CIGS/indium sulfide.

A copper indium gallium selenide thin film solar cell was fabricated by the structure of soda lime glass/Mo/CIGS/indium sulfide/i-ZnO/ITO, and the solar indium gallium selenide thin film solar cell was analyzed by a solar standard light source simulator. The experiment showed that the open circuit voltage (Voc) The current is 0.394V, the short-circuit current (Jsc) is 32.36 mA/cm ² , the fill factor (FF) is 51.03%, and the photoelectric conversion efficiency is 6.51%. Compared with the comparative example 5 in the post-heating section, the open circuit voltage, short-circuit current, fill factor and conversion efficiency of the indium sulfide (PAT) film applied to the copper indium gallium selenide thin film were significantly increased.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and retouched without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

1‧‧‧Solar battery
10‧‧‧Substrate
20‧‧‧Back electrode
30‧‧‧Light absorbing layer
40‧‧‧buffer layer
50‧‧‧ Transparent window layer
60‧‧‧ front electrode

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

Claims (9)

A method for manufacturing a buffer layer for a solar cell, comprising: providing a precursor solution comprising: a solvent; a main metal element selected from the group consisting of zinc, cadmium, indium, and combinations thereof; Group VIA element, Selecting a group consisting of oxygen, sulfur, selenium, and combinations thereof; and doping elements selected from the group consisting of titanium, lead, tin, nickel, ruthenium, osmium, and combinations thereof; contacting a laminate structure with the precursor a solution to form a deposited layer on the laminated structure, wherein the laminated structure comprises a light absorbing layer, the compound structure of the light absorbing layer is a chalcopyrite phase, a zinc tin ore phase, a sphalerite phase, a kersterite structure Or the combination of the above, the step of contacting the laminate structure with the precursor solution comprises contacting the light absorbing layer of the laminate structure with the precursor solution to form the deposition layer on the light absorbing layer; and depositing the deposition layer A heat treatment is performed under the atmosphere to form a buffer layer on the light absorbing layer, wherein the atmosphere contains a Group VIA element, and the heat treatment temperature is from 50 ° C to 300 ° C. The method of claim 1, wherein the atmosphere The Group VIA element comprises sulfur, selenium, oxygen or a combination thereof. The method of claim 1, wherein the atmosphere comprises hydrogen sulfide, hydrogen selenide, sulfur vapor, selenium vapor, or a combination thereof. The method of claim 1, wherein the atmosphere further comprises hydrogen, an inert gas, or a combination thereof. The method of claim 4, wherein the inert gas is nitrogen, argon or a combination thereof. The method of claim 1, wherein the heat treatment is performed for 10 minutes to 8 hours. The method of claim 1, wherein the precursor solution further comprises a hydroxide ion. The method of claim 1, wherein the laminate further comprises a substrate and a back electrode on the substrate and below the light absorbing layer. The method of claim 1, wherein the precursor solution further comprises an acid or a base.