阅读说明：本技术 Cu基薄膜太阳电池光吸收层后处理及沉积缓冲层的方法 (Method for post-treatment and buffer layer deposition of light absorption layer of Cu-based thin film solar cell ) 是由 李建民 宫俊波 孔一帆 肖旭东 于 2018-09-13 设计创作，主要内容包括：本发明公开了一种Cu基薄膜太阳电池光吸收层后处理及沉积缓冲层的方法,所述后处理方法包括如下步骤：(1)配置氨水溶液,所述氨水溶液的浓度为0.1-1M；(2)将光吸收层按所述光吸收层的待处理表面与所述氨水溶液的液面呈预定角度放置在所述氨水溶液中进行处理1-10min,处理温度为25-65℃；(3)取出处理后的光吸收层,清洗后吹干。本发明可以改善光吸收层的表面成分及形貌,以更利于光吸收层和缓冲层Zn(O,S)的之间的相互扩散,在沉积缓冲层Zn(O,S)时,Zn(O,S)薄膜的晶粒更大,最终制备得到的Cu基薄膜太阳电池的性能得到了提高,同时大幅度减弱了光浸润效应。(The invention discloses a method for post-processing and depositing a buffer layer on a light absorption layer of a Cu-based thin film solar cell, which comprises the following steps: (1) preparing an ammonia water solution, wherein the concentration of the ammonia water solution is 0.1-1M; (2) placing the light absorption layer in the ammonia water solution according to a preset angle formed by the surface to be processed of the light absorption layer and the liquid level of the ammonia water solution, and processing for 1-10min at the temperature of 25-65 ℃; (3) the treated light absorbing layer was taken out, washed and then dried by blowing. The invention can improve the surface composition and the morphology of the light absorption layer, is more beneficial to the mutual diffusion between the light absorption layer and the buffer layer Zn (O, S), has larger crystal grains of the Zn (O, S) film when the buffer layer Zn (O, S) is deposited, improves the performance of the finally prepared Cu-based film solar cell, and simultaneously greatly weakens the light infiltration effect.)

1. A post-processing method for a light absorption layer of a Cu-based thin film solar cell is characterized by comprising the following steps:

(1) preparing an ammonia water solution, wherein the concentration of the ammonia water solution is 0.1-1M;

(2) placing the light absorption layer in the ammonia water solution according to a preset angle formed by the surface to be processed of the light absorption layer and the liquid level of the ammonia water solution, and processing for 1-10min at the temperature of 25-65 ℃;

(3) the treated light absorbing layer was taken out, washed and then dried by blowing.

2. The method of post-treating a light-absorbing layer according to claim 1, wherein: the light absorbing layer is a CIGS light absorbing layer or a CZTS light absorbing layer.

3. The method for post-treating a light-absorbing layer according to claim 1 or 2, wherein: the light absorption layer is prepared by adopting a co-evaporation three-step method.

4. The method for post-treating a light-absorbing layer according to claim 1 or 2, wherein: the predetermined angle is 65-90 deg..

5. A method of depositing a buffer layer on a light absorbing layer of a Cu-based thin film solar cell, the buffer layer being Zn (O, S), comprising the steps of:

(1) firstly, mixing and stirring a zinc source solution and a complexing agent solution for a first time, then simultaneously adding a thioacetamide solution and an ammonia water solution, mixing and stirring for a second time to prepare a deposition solution, wherein Zn of a zinc source in the deposition solution²⁺The concentration is 2.5-10mM, the concentration of the complexing agent is 2.5-13mM, and the S of thioacetamide^2-The concentration is 5-12.5mM, and the concentration of ammonia water is 0.7-2.2M;

(2) immersing the light absorbing layer treated by the post-treatment method according to any one of claims 1 to 4 in the deposition solution, and depositing a buffer layer Zn (O, S) on the light absorbing layer by heating in a water bath;

(3) taking out the sample after the deposition is finished, washing the sample with deionized water, then cleaning the surface of the sample with 0.1-1M ammonia water solution at the temperature of 20-60 ℃, removing the residual ammonia water solution with the deionized water, and drying the sample;

(4) and (4) heating the sample treated in the step (3) in air at the temperature of 60-160 ℃ for 1-8 min.

6. The method of claim 5, wherein the first time in step (1) is 1-10 min; the second time is 10-30 s.

7. The method of claim 5, wherein the zinc source is at least one of zinc acetate, zinc sulfate, and zinc chloride; the complexing agent is at least one of citric acid and trisodium citrate.

8. The method of claim 5, wherein the zinc source is zinc acetate, Zn²⁺The concentration in the deposition solution was 7.5 mM; the complexing agent is citric acid, the concentration of which in the deposition solution is 6.5 mM; s of thioacetamide in the deposition solution^2-The concentration was 7.5mM and the concentration of ammonia was 1.4M.

9. The preparation method of the thin film solar cell is characterized by comprising the following steps:

(1) depositing a back electrode layer on a substrate and depositing a light absorbing layer on the back electrode layer;

(2) treating the light absorbing layer using the post-treatment method of any one of claims 1 to 4;

(3) depositing a buffer layer Zn (O, S) on the light absorbing layer using the method of any one of claims 5 to 8;

(4) depositing a window layer on the buffer layer Zn (O, S), and forming a gate on the window layer.

10. The method of manufacturing of claim 9, wherein the substrate is soda lime glass; the back electrode is Mo; the window layer is magnesium-doped zinc oxide and aluminum-doped zinc oxide; the gate is a Ni-Al gate.

Technical Field

The invention relates to the technical field of thin film solar cells, in particular to a method for post-processing and depositing a buffer layer on a light absorption layer of a Cu-based thin film solar cell.

Background

In the existing thin film solar cell preparation process, in the process of depositing the cadmium-free buffer layer Zn (O, S) on the Light absorption layer, the diffusion of Zn on the surface of the buffer layer is difficult, and high-temperature (200 ℃) treatment is usually needed. The existence of these problems can cause the performance degradation of the thin film solar cell based on the cadmium-free Zn (O, S) buffer layer and cause certain obstacles to the marketing process of the thin film solar cell.

Disclosure of Invention

In order to make up for the defects of the prior art, the invention provides a method for post-processing a light absorption layer of a Cu-based thin film solar cell and depositing a buffer layer.

The technical problem of the invention is solved by the following technical scheme:

a post-treatment method for a light absorption layer of a Cu-based thin film solar cell comprises the following steps:

(1) preparing an ammonia water solution, wherein the concentration of the ammonia water solution is 0.1-1M;

(2) placing the light absorption layer in the ammonia water solution according to a preset angle formed by the surface to be processed of the light absorption layer and the liquid level of the ammonia water solution, and processing for 1-10min at the temperature of 25-65 ℃;

(3) the treated light absorbing layer was taken out, washed and then dried by blowing.

Preferably, the light absorbing layer is a CIGS light absorbing layer or a CZTS light absorbing layer.

Preferably, the light absorption layer is prepared by adopting a co-evaporation three-step method.

Preferably, the predetermined angle is 65-90 °.

A method of depositing a buffer layer on a light absorbing layer of a Cu-based thin film solar cell, the buffer layer being Zn (O, S), comprising the steps of:

(1) firstly, mixing and stirring a zinc source solution and a complexing agent solution for a first time, then simultaneously adding a thioacetamide solution and an ammonia water solution, mixing and stirring for a second time to prepare a deposition solution, wherein Zn of a zinc source in the deposition solution²⁺The concentration is 2.5-10mM, the concentration of the complexing agent is 2.5-13mM, and the S of thioacetamide^2-The concentration is 5-12.5mM, and the concentration of ammonia water is0.7-2.2M；

(2) Immersing the light absorption layer treated by the post-treatment method into the deposition solution, and depositing a buffer layer Zn (O, S) on the light absorption layer by water bath heating;

(3) taking out the sample after the deposition is finished, washing the sample with deionized water, then cleaning the surface of the sample with 0.1-1M ammonia water solution at the temperature of 20-60 ℃, removing the residual ammonia water solution with the deionized water, and drying the sample;

(4) and (4) heating the sample treated in the step (3) in air at the temperature of 60-160 ℃ for 1-8 min.

Preferably, the first time in the step (1) is 1-10min, and the second time is 10-30 s.

Preferably, the zinc source is at least one of zinc acetate, zinc sulfate and zinc chloride; the complexing agent is at least one of citric acid and trisodium citrate.

Preferably, the zinc source is zinc acetate, Zn²⁺The concentration in the deposition solution was 7.5 mM; the complexing agent is citric acid, the concentration of which in the deposition solution is 6.5 mM; s of thioacetamide in the deposition solution^2-The concentration was 7.5mM and the concentration of ammonia was 1.4M.

A preparation method of a thin film solar cell comprises the following steps:

(1) depositing a back electrode layer on a substrate and depositing a light absorbing layer on the back electrode layer;

(2) treating the light absorption layer by the post-treatment method;

(3) depositing a buffer layer Zn (O, S) on the light absorption layer by adopting the method;

(4) depositing a window layer on the buffer layer Zn (O, S), and forming a gate on the window layer.

Preferably, the substrate is soda lime glass; the back electrode is Mo.

Preferably, the window layer is magnesium doped zinc oxide and aluminum doped zinc oxide; the gate is a Ni-Al gate.

Compared with the prior art, the invention has the advantages that:

after the surface to be processed of the light absorption layer and the liquid level of the ammonia water solution are placed at a preset angle, the light absorption layer of the Cu-based thin film solar cell is subjected to surface processing (selective etching) by using the low-concentration ammonia water solution, so that the surface composition and the appearance of the light absorption layer can be improved, mutual diffusion between the light absorption layer and the buffer layer Zn (O, S) is facilitated, and crystal grains of the Zn (O, S) thin film are larger when the buffer layer Zn (O, S) is deposited. By the method, the performance of the finally prepared Cu-based thin film solar cell is improved, and meanwhile, the light infiltration effect is greatly weakened, so that the production and marketing of the Cu-based thin film solar cell based on the cadmium-free Zn (O, S) buffer layer are promoted.

Drawings

Fig. 1a and 1b are SEM images of an untreated CIGS light absorbing layer and a CIGS light absorbing layer treated by a method according to a first embodiment of the present invention, respectively;

FIGS. 2a and 2b are SEM images of a second sample and a first sample, respectively, in a second embodiment of the present invention;

FIG. 2c is an XPS plot of a third sample and a first sample in example two of the present invention; FIG. 2d is a J-V plot of the resulting battery devices of the third and first samples;

fig. 3a and 3b are TEM images of a second device and a first device, respectively, in a third embodiment of the present invention;

fig. 4 (a) and (b) are EDX diagrams of a second device and a first device, respectively, in the third embodiment of the present invention;

FIGS. 5a and 5b are J-V graphs of a second device and a first device, respectively, in a third embodiment of the present invention;

FIGS. 6a and 6b are SEM images of an untreated CZTS light absorbing layer and a CZTS light absorbing layer treated in the fourth example, respectively;

fig. 7 is a J-V graph of the third device and the fourth device in the fifth embodiment of the present invention.

Detailed Description

The invention will be further described with reference to the accompanying drawings and preferred embodiments. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The specific embodiment of the invention provides a post-treatment method for a light absorption layer of a Cu-based thin film solar cell, which comprises the following steps:

(1) preparing an ammonia water solution, wherein the concentration of the ammonia water solution is 0.1-1M;

(2) placing the light absorption layer in an ammonia water solution at a predetermined angle with respect to the surface of the light absorption layer to be treated and the liquid level of the ammonia water solution, and treating for 1-10min at 25-65 ℃;

(3) the treated light absorbing layer was taken out, washed and then dried by blowing.

Wherein, in the surface treatment process of the light absorption layer, the sample deposited with the light absorption layer is immersed in the aqueous ammonia solution in such a manner that the surface to be treated of the light absorption layer and the liquid level of the aqueous ammonia solution form a predetermined angle, preferably, the predetermined angle is 65 to 90 °, more preferably, the predetermined angle is 90 °. The selective etching can be carried out on the surface of the light absorption layer by a placing mode that the surface to be processed of the light absorption layer and the liquid level of the ammonia water solution form a preset angle, and generated bubbles can be timely removed in the process that the surface of the light absorption layer is etched by the ammonia water, so that the processing is more uniform, the growth of a follow-up Zn (O, S) buffer layer is more favorable, and a smoother buffer layer film is formed.

Preferably, the light absorbing layer is CIGS (Cu (In, Ga) Se₂Copper indium gallium selenide) light absorbing layer or CZTS (Cu)₂ZnSnS₄Copper zinc tin sulfide) light absorbing layer.

Preferably, the light absorption layer is prepared by adopting a co-evaporation three-step method. Taking the CIGS light absorbing layer as an example, the process of the co-evaporation three-step method is as follows: the first step is as follows: co-evaporating In, Ga and Se to deposit on the substrate to form an In-Ga-Se layer; the second step is that: co-evaporating Cu and Se to deposit on the In-Ga-Se layer to form a Cu-rich CIGS layer; the third step: small amounts of In, Ga and Se are deposited to form copper-depleted CIGS thin films. Impurities such as Se, oxide, Na aggregates and the like may exist on the surface of the light absorption layer formed by the three-step method, and the surface of the light absorption layer is selectively etched by the low-concentration ammonia water solution, so that the surface composition and the appearance can be improved.

The embodiment of the present invention also provides a method for depositing a buffer layer on a light absorption layer of a Cu-based thin film solar cell, the buffer layer being Zn (O, S), comprising the steps of:

(1) firstly, mixing and stirring a zinc source solution and a complexing agent solution for a first time, then simultaneously adding a thioacetamide solution and an ammonia water solution, mixing and stirring for a second time to prepare a deposition solution, wherein Zn of a zinc source in the deposition solution²⁺The concentration is 2.5-10mM, the concentration of the complexing agent is 2.5-13mM, and the S of thioacetamide^2-The concentration is 5-12.5mM, and the concentration of ammonia water is 0.7-2.2M;

(2) immersing the light absorption layer treated by the post-treatment method in the above embodiment in the deposition solution, and depositing a buffer layer Zn (O, S) on the light absorption layer by heating in a water bath;

(3) taking out the sample after the deposition is finished, washing the sample with deionized water, then cleaning the surface of the sample with 0.1-1M ammonia water solution at the temperature of 20-60 ℃, removing the residual ammonia water solution with the deionized water, and drying the sample;

(4) and (4) heating the sample treated in the step (3) in air at the temperature of 60-160 ℃ for 1-8 min.

Preferably, the first time in step (1) is 1-10 min; the second time is 10-30 s.

Preferably, the zinc source is at least one of zinc acetate, zinc sulfate and zinc chloride; the complexing agent is at least one of citric acid and trisodium citrate. More preferably, the zinc source is zinc acetate Zn (COOH)₂·2H₂O，Zn²⁺The concentration in the deposition solution is 7.5mM, and the complexing agent is citric acid C₆H₈O₇·H₂O, the concentration of which in the deposition solution is 6.5 mM; thioacetamide C₂H₅S of NS^2-The concentration in the bath was 7.5mM and the concentration of ammonia in the bath was 1.4M.

The specific embodiment of the invention also provides a preparation method of the thin film solar cell, which comprises the following steps:

(1) depositing a back electrode layer on a substrate and depositing a light absorbing layer on the back electrode layer;

(2) treating the light absorbing layer by the post-treatment method in the above embodiment;

(3) depositing a buffer layer Zn (O, S) on the light absorbing layer using the method in the above embodiment;

(4) depositing a window layer on the buffer layer Zn (O, S), and forming a gate on the window layer.

Preferably, the substrate is soda lime glass; the back electrode is Mo and the light absorbing layer can be formed by a co-evaporation three-step method.

Preferably, the window layer is magnesium doped zinc oxide (ZnMgO) and aluminum doped zinc oxide (Al: ZnO), which can be deposited by magnetron sputtering.

Preferably, the grid is a Ni-Al grid, which may be formed by electron beam evaporation.

The present invention will be further described below by taking a CIGS thin film solar cell as an example.