Thin film solar cell and preparation method thereof

Abstract

The invention discloses a thin-film solar cell and a preparation method thereof, and belongs to the technical field of solar cells. According to the thin-film solar cell provided by the invention, after cadmium selenide is deposited on the surface of the substrate material, pretreatment is carried out under specific pressure and temperature, so that nucleation and crystal nucleus growth of cadmium selenide can be ensured under the condition that the number of cadmium telluride sources is the same as that of cadmium selenide sources, and then cadmium telluride is deposited and cadmium chloride is introduced; and internal defects of the cadmium selenide film layer can be effectively eliminated, so that the conversion efficiency of the cadmium telluride thin film solar cell can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a thin-film solar cell and a preparation method thereof. Background Art

[0002] The preparation process of cadmium telluride (CdTe) thin film battery currently mainly adopts high temperature deposition method of close space sublimation (CSS) and vapor transport deposition (VTD). Due to the relationship between the saturated vapor pressure of cadmium selenide (CdSe) and CdTe materials and temperature and vacuum degree, the deposition rate of CdTe is greater than that of CdSe, and in the thin film battery structure, the thickness requirement of CdTe is much greater than that of CdSe. In order to ensure that the needs of the device are met, the temperature of the CdTe source is often greater than that of CdSe, or the number of CdTe sources is greater than that of CdSe sources. If the number of CdTe sources and CdSe sources is the same, the temperature of the CdTe source is greater than that of the CdSe source. In this case, after the CdSe thin film deposited on the glass passes through the CdTe source, the CdSe anti-sublimation phenomenon occurs, which affects the nucleation and growth process (grain growth) of CdSe, and even stripe defects may occur on the glass, reducing the characteristics of the PN junction and affecting the conversion efficiency of the thin film battery. Summary of the invention

[0003] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a thin film solar cell with good photoelectric conversion efficiency and a preparation method thereof.

[0004] To achieve the above object, in a first aspect of the present invention, the present invention provides a method for preparing a thin film solar cell, the preparation method comprising the following steps:

[0005] (1) depositing cadmium selenide on the surface of the substrate material and then pre-treating the surface to form a cadmium selenide film layer;

[0006] (2) depositing cadmium telluride on the surface of the cadmium selenide film layer to form a cadmium telluride film layer;

[0007] (3) introducing a cadmium chloride film layer onto the surface of the cadmium telluride film layer and then subjecting it to high temperature treatment;

[0008] (4) laser scribing and deposition of back electrodes after high temperature treatment, followed by annealing, encapsulation and lamination to obtain a thin film solar cell;

[0009] In the step (1), the pretreatment pressure is ≤100 Pa, and the pretreatment temperature is 350-600°C.

[0010] A thin-film solar cell provided by the present invention can ensure the nucleation and crystal nucleus growth of cadmium selenide when the amount of cadmium telluride source and cadmium selenide source is the same by pre-treating cadmium selenide on the surface of a substrate material under a specific pressure and temperature, and then depositing cadmium telluride and introducing cadmium chloride, etc., which can effectively eliminate the internal defects of the cadmium selenide film layer, thereby effectively improving the conversion efficiency of the thin-film solar cell.

[0011] Exemplarily, in the step (1), the pretreatment pressure may be any point value or any range value between ≤100Pa, for example, 50-100Pa, 80-100Pa, 50-80Pa, etc., or may be 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa, etc.; the pretreatment temperature may be any point value or any range value between 350-600℃, for example, 350℃, 380℃, 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, etc.

[0012] Preferably, in step (1), the pretreatment pressure is 50-100 Pa.

[0013] Preferably, in step (1), the pretreatment temperature is 500-600°C.

[0014] The present invention has found that when the pressure and temperature of the pretreatment are further selected to be within the above range, the conversion efficiency of the obtained thin-film solar cell is higher.

[0015] Exemplarily, the pretreatment environment may be a vacuum environment of ≤100 Pa, or an inert gas environment of ≤100 Pa.

[0016] The vacuum environment of ≤100 Pa is to evacuate the system to a pressure of ≤100 Pa. The inert gas environment of ≤100 Pa is to evacuate the system to a pressure of ≤0.001 Pa and then introduce inert gas to a pressure of ≤100 Pa.

[0017] Exemplarily, the inert gas includes argon.

[0018] As a preferred embodiment of the preparation method of the present invention, in the step (1), the pretreatment time is 5-15 minutes.

[0019] Exemplarily, in step (1), the pretreatment time can be any point value or any two point range values ​​between 5-15 minutes, such as 5 minutes, 10 minutes, 15 minutes, etc.

[0020] As a preferred embodiment of the preparation method of the present invention, in the step (1), the deposition temperature is 500-600°C.

[0021] Exemplarily, in step (1), the deposition temperature may be any point value between 500-600°C or any two points in the range, such as 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, etc.

[0022] As a preferred embodiment of the preparation method of the present invention, in the step (1), the thickness of the cadmium selenide film layer is 80-150 nm.

[0023] Exemplarily, in step (1), the thickness of the cadmium selenide film layer can be any point value or any two point range values ​​between 80-150nm, for example, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, etc.

[0024] Preferably, in step (1), the thickness of the cadmium selenide film layer is 90-110 nm.

[0025] As a preferred embodiment of the preparation method of the present invention, in the step (2), the deposition temperature is 500-600°C.

[0026] Exemplarily, in step (2), the deposition temperature may be any point value between 500-600°C or any two points in the range, such as 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, etc.

[0027] As a preferred embodiment of the preparation method of the present invention, in the step (2), the thickness of the cadmium telluride film layer is 2000-4000nm.

[0028] Exemplarily, in step (2), the thickness of the cadmium telluride film layer may be any point value or any two point range value between 2000-4000nm, for example, it may be 2000nm, 2200nm, 2400nm, 2600nm, 2800nm, 3000nm, 3200nm, 3400nm, 3600nm, 3800nm, 4000nm, etc.

[0029] Preferably, in step (2), the thickness of the cadmium telluride film layer is 2800-3200 nm.

[0030] The present invention has found that when the deposition temperature and thickness of the cadmium selenide film layer and the cadmium telluride film layer are further selected within the above range, the conversion efficiency of the obtained thin-film solar cell is higher and the overall performance is better.

[0031] As a preferred embodiment of the preparation method of the present invention, in the step (3), the introducing is achieved by evaporation or wet coating.

[0032] Preferably, in step (3), the introducing is achieved by a wet coating method.

[0033] Further selection of wet coating can better improve work efficiency and is conducive to the mass production of thin-film solar cells.

[0034] The present invention has no special requirements on the parameters of evaporation or wet coating, and the evaporation method or wet coating method commonly used in the art can be adopted. For example, in wet coating, the coating time is 30-60s and the solution concentration is 300-600g / L.

[0035] As a preferred embodiment of the preparation method of the present invention, in the step (3), the thickness of the cadmium chloride film layer is 50-100 μm.

[0036] Exemplarily, in step (3), the thickness of the cadmium chloride film layer can be any point value or any two point range value between 50-100 μm, such as 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.

[0037] As a preferred embodiment of the preparation method of the present invention, in the step (3), the temperature of the high temperature treatment is 350-500° C., and the time of the high temperature treatment is 15-40 min.

[0038] Exemplarily, in the step (3), the temperature of the high temperature treatment may be any point value or any two point range value between 350-500°C, for example, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, etc.; the time of the high temperature treatment may be any point value or any two point range value between 15-40min, for example, 15min, 20min, 25min, 30min, 35min, 40min, etc.

[0039] As a preferred embodiment of the preparation method of the present invention, in the step (4), the annealing temperature is 250-320° C., and the annealing time is 20-30 min.

[0040] Exemplarily, in the step (4), the annealing temperature may be any point value or any two point range value between 250-320°C, for example, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, etc.; the annealing time may be any point value or any two point range value between 20-30min, for example, 20min, 22min, 24min, 26min, 28min, 30min, etc.

[0041] As a preferred embodiment of the preparation method of the present invention, the substrate material includes FTO glass.

[0042] The present invention has no special requirements for laser scribing and scribing width, and P1, P2, P3, and P4 scribing is performed according to the conventional scribing method and scribing width in the art. For example, the P1 line width is 20-40 μm, the P2 line width is 40-70 μm, and the P3 line width is 30-50 μm.

[0043] The present invention has no special requirements for depositing the back electrode, and the back electrode is deposited in a conventional manner in the art, such as by magnetron sputtering, with a deposition temperature of 20-30° C. and a deposition thickness of 200-400 nm.

[0044] The present invention has no special requirements for the selection of the back electrode, and any back electrode conventionally used in the art can be used, for example, an aluminum back electrode or a silver back electrode.

[0045] The present invention has no special requirements on the parameters of packaging lamination, and it is carried out according to the conventional packaging lamination method in the art.

[0046] In a second aspect of the present invention, the present invention provides a thin film solar cell, wherein the thin film solar cell is prepared by the preparation method of the present invention.

[0047] As a preferred embodiment of the thin film solar cell of the present invention, the conversion efficiency of the thin film solar cell is ≥14.3%.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] A thin-film solar cell provided by the present invention can ensure the nucleation and crystal nucleus growth of cadmium selenide when the amount of cadmium telluride source and cadmium selenide source is the same by pre-treating cadmium selenide on the surface of a substrate material under a specific pressure and temperature, and then depositing cadmium telluride and introducing cadmium chloride, etc., which can effectively eliminate the internal defects of the cadmium selenide film layer and effectively improve the conversion efficiency of the thin-film solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1This is a SEM observation result of the cadmium selenide film layer in the product prepared in Example 1;

[0051] Figure 2 This is a SEM observation result of the cadmium selenide film layer in the product prepared in Example 2;

[0052] Figure 3 This is a SEM observation result of the cadmium selenide film layer in the product prepared in Comparative Example 1. DETAILED DESCRIPTION

[0053] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0054] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0055] Unless otherwise specified, the materials and equipment used in parallel experiments were kept consistent.

[0056] Example 1

[0057] An embodiment of the present invention provides a thin film solar cell, wherein a method for preparing the thin film solar cell comprises the following steps:

[0058] (1) CdSe was deposited on FTO glass by vapor transport deposition, wherein the temperature of the CdSe source in the vapor transport deposition was 600°C, and then the FTO glass after CdSe deposition was transferred to a buffer chamber in a vapor transport deposition device, the buffer chamber was evacuated to a system pressure of 0.001Pa, and then argon gas was added to a system pressure of 80Pa, the temperature of the buffer chamber was 600°C, and the FTO glass after CdSe deposition was allowed to stay in the buffer chamber for 10 minutes; forming a CdSe film layer with a thickness of 100nm;

[0059] (2) transferring the workpiece after the cadmium selenide film layer is formed to a cadmium telluride source (temperature is 700° C.) and depositing cadmium telluride on the surface of the cadmium selenide film layer to form a cadmium telluride film layer with a thickness of 3000 nm;

[0060] (3) introducing a cadmium chloride film layer with a thickness of 80 μm on the surface of the cadmium telluride film layer by wet coating, heating it to 420° C. and maintaining it for 25 minutes for high temperature treatment;

[0061] (4) After the high temperature treatment, laser P1 / P2 / P3 / P4 scribing is performed, followed by deposition of the back electrode, followed by annealing at 300°C for 25 minutes, and finally encapsulation and lamination to obtain a thin film solar cell.

[0062] Example 2

[0063] An embodiment of the present invention provides a thin film solar cell, wherein a method for preparing the thin film solar cell comprises the following steps:

[0064] (1) CdSe was deposited on FTO glass by vapor transport deposition, wherein the temperature of the CdSe source in the vapor transport deposition was 600°C, and then the FTO glass after CdSe deposition was transferred to a buffer chamber in a vapor transport deposition device, the buffer chamber was evacuated to a system pressure of 80 Pa, the temperature of the buffer chamber was 500°C, and the FTO glass after CdSe deposition was kept in the buffer chamber for 10 minutes; thus, a CdSe film layer with a thickness of 140 nm was formed;

[0065] (2) transferring the workpiece after the cadmium selenide film layer is formed to a cadmium telluride source (temperature is 700° C.) and depositing cadmium telluride on the surface of the cadmium selenide film layer to form a cadmium telluride film layer with a thickness of 3000 nm;

[0066] (3) introducing a cadmium chloride film layer with a thickness of 80 μm on the surface of the cadmium telluride film layer by wet coating, heating it to 420° C. and maintaining it for 25 minutes for high temperature treatment;

[0067] (4) After the high temperature treatment, laser P1 / P2 / P3 / P4 scribing is performed, followed by deposition of the back electrode, followed by annealing at 300°C for 25 minutes, and finally encapsulation and lamination to obtain a thin film solar cell.

[0068] Examples 3-12 and Comparative Examples 1-4

[0069] Embodiments 3-12 of the present invention and comparative examples 1-4 provide a thin film solar cell, and the only difference between the method for preparing the thin film solar cell and embodiment 1 is shown in Table 1;

[0070] Table 1

[0071]

[0072]

[0073] The “ / ” in Comparative Example 1 represents that Comparative Example 1 has no pretreatment process compared with Example 1.

[0074] Effect example

[0075] The effect examples of the present invention explore the performance of the thin-film solar cells prepared by Examples 1-12 and Comparative Examples 1-4, including the average grain size of cadmium selenide in the cadmium selenide film layer and the conversion efficiency of the thin-film solar cells; wherein the average grain size is measured by a SEM scanning electron microscope, and the conversion efficiency is measured by an IV tester; the results obtained are shown in Table 2;

[0076] Table 2

[0077]

[0078] It can be seen from Table 2 that when the technical solution provided by the present invention is adopted, the crystal particle size of cadmium selenide in the obtained thin-film solar cell is relatively large, that is, the crystallization degree of cadmium selenide can be well improved, thereby effectively improving the photoelectric conversion efficiency of the thin-film solar cell, and the conversion efficiency of the obtained product is above 14.3%; at the same time, the cadmium selenide film layer of the product prepared in Example 1-2 and Comparative Example 1 is observed by SEM, and the result graphs obtained are respectively as follows: Figure 1-3 As shown, from Figure 1-3 It can be seen that the degree of crystallization of the cadmium selenide film layer obtained in Examples 1-2 of the present invention is significantly better than the degree of crystallization of the cadmium selenide film layer of the product in Comparative Example 1.

[0079] It can also be seen from Example 1 and Comparative Example 2 that the pressure during the pretreatment process will affect the overall effect of the product. When the pretreatment pressure in Comparative Example 2 is too large, the conversion efficiency of the obtained product is significantly reduced. It can be seen from Example 1 and Comparative Examples 3-4 that the temperature during the pretreatment process will also affect the conversion efficiency of the product. When the pretreatment temperature in Comparative Examples 3-4 is not within the range given in the present invention, the photoelectric conversion efficiency of the obtained product is significantly reduced.

[0080] Finally, it should be noted that the above embodiments are intended to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a thin film solar cell, characterized in that: The preparation method comprises the following steps: (1) depositing cadmium selenide on the surface of the substrate material and then pre-treating the surface to form a cadmium selenide film layer; (2) depositing cadmium telluride on the surface of the cadmium selenide film layer to form a cadmium telluride film layer; (3) introducing a cadmium chloride film layer onto the surface of the cadmium telluride film layer and then subjecting it to high temperature treatment; (4) laser scribing and deposition of back electrodes after high temperature treatment, followed by annealing, encapsulation and lamination to obtain a thin film solar cell; In the step (1), the pretreatment pressure is ≤100 Pa, and the pretreatment temperature is 350-600°C.

2. The preparation method according to claim 1, characterized in that: In the step (1), the pretreatment time is 5-15 minutes.

3. The preparation method according to claim 1, characterized in that: In the step (1), the deposition temperature is 500-600°C; And / or, in step (1), the thickness of the cadmium selenide film layer is 80-150nm.

4. The preparation method according to claim 1, characterized in that: In the step (2), the deposition temperature is 500-600°C; And / or, in step (2), the thickness of the cadmium telluride film layer is 2000-4000nm.

5. The preparation method according to claim 1, characterized in that: In the step (3), the introducing is achieved by evaporation or wet coating; And / or, in step (3), the thickness of the cadmium chloride film layer is 50-100 μm.

6. The preparation method according to claim 1, characterized in that: In the step (3), the temperature of the high temperature treatment is 350-500° C., and the time of the high temperature treatment is 15-40 minutes.

7. The preparation method according to claim 1, characterized in that: In the step (4), the annealing temperature is 250-320° C., and the annealing time is 20-30 min.

8. The preparation method according to claim 1, characterized in that: The substrate material includes FTO glass.

9. A thin film solar cell, characterized in that: The thin film solar cell is prepared by the preparation method according to any one of claims 1 to 8.

10. The thin film solar cell according to claim 9, characterized in that: The conversion efficiency of the thin film solar cell is ≥14.3%.

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