Flexible copper indium gallium selenide cell and method of making same

Abstract

The present disclosure relates to a flexible copper indium gallium selenide cell and a preparation method thereof. The flexible copper indium gallium selenide cell comprises a P-N junction and a composite window layer covering the P-N junction. The composite window layer comprises a transparent conductive film covering the P-N junction and a high-resistance film covering the transparent conductive film. The transparent conductive film is arranged between the high-resistance film and the P-N junction, so that the positive charges and free electrons can move freely in the transparent conductive film. The free-moving positive charges and free electrons can neutralize each other, so that the charges generated in the deposition process of the high-resistance film can be eliminated, the charge accumulation phenomenon is avoided, the subsequent particle deposition is not affected, the local thinning problem is avoided, the uniformity of the high-resistance film is ensured, and the uniformity of the copper indium gallium selenide cell is improved.

Description

Technical Field

[0001] This disclosure relates to the field of photovoltaic cell technology, specifically to a flexible copper indium gallium selenide (CIGS) cell and its preparation method. Background Technology

[0002] With the development of photovoltaic cell technology, in order to obtain copper indium gallium selenide (CIGS) cells with better performance, the thickness of the high-resistivity layer is constantly decreasing. As the thickness of the high-resistivity layer decreases, the requirements for the uniformity of its thickness become increasingly stringent.

[0003] In related technologies, the high-resistivity layer of flexible copper indium gallium selenide (CIGS) solar cells is deposited on the surface of the PN junction. However, due to the non-conductive nature of the high-resistivity layer itself, charge accumulation occurs during the rapid deposition process, which affects the subsequent deposition of particles. This leads to local thinning of the high-resistivity layer, resulting in uneven thickness and affecting the performance of the photovoltaic cells formed. Summary of the Invention

[0004] The purpose of this disclosure is to provide a flexible copper indium gallium selenide (CIGS) battery and its fabrication method to solve the problems in the aforementioned related technologies.

[0005] To achieve the above objectives, one aspect of this disclosure provides a flexible copper indium gallium selenide (CIGS) battery, comprising: PN junction; A composite window layer covering the PN junction; The composite window layer comprises a transparent conductive film and a high-resistivity film, wherein the transparent conductive film covers the PN junction and the high-resistivity film covers the transparent conductive film.

[0006] Optionally, the transparent conductive film includes an ITO film, an ICO film, or an AZO film.

[0007] Optionally, the ITO thin film is fabricated using an ITO target doped with indium tin oxide via magnetron sputtering, with the tin oxide doping ratio being 2%-10% wt%. The ICO thin film is fabricated using an ICO target doped with indium cerium oxide via magnetron sputtering, with a cerium oxide doping ratio of 2%-10% wt%. The AZO thin film is made by magnetron sputtering of AZO target doped with aluminum zinc oxide. The doping ratio of aluminum oxide is 1%-3%wt.

[0008] Optionally, the thickness of the transparent conductive film is set to 5nm-50nm.

[0009] Optionally, the resistivity of the transparent conductive film is set to be less than 2E-3Ω•cm.

[0010] Optionally, the high-resistivity film is configured as a ZnO film or a ZMO film.

[0011] Optionally, the thickness of the high-resistivity film is set to 5nm-45nm.

[0012] Optionally, the PN junction includes a back electrode film system, an absorption layer, and a buffer layer, wherein the absorption layer covers the back electrode film system, the buffer layer covers the absorption layer, and the transparent conductive film covers the buffer layer.

[0013] Optionally, the flexible copper indium gallium selenide (CIGS) cell further includes a substrate, a transparent conductive front electrode, and grid lines; The back electrode film is covered on the substrate, and the transparent conductive front electrode and the gate line are covered on the high-resistivity thin film. The substrate is configured as a flexible metal substrate, which includes a stainless steel substrate, a Ti alloy substrate, or a single metal substrate.

[0014] A second aspect of this disclosure also provides a method for preparing the above-mentioned flexible copper indium gallium selenide (CIGS) solar cell, comprising the following steps: Preparation of PN junction; A transparent conductive film is coated on the PN junction using a magnetron sputtering process; A high-resistivity film is coated onto the transparent conductive film using a magnetron sputtering process.

[0015] The above technical solution involves placing a transparent conductive film between the high-resistivity film and the PN junction. In other words, the high-resistivity film is deposited on the upper surface of the transparent conductive film during its formation. The conductivity of the transparent conductive film allows positive charges and free electrons to move freely within it. These freely moving positive charges and free electrons can combine and neutralize each other, thereby eliminating the charge generated during the deposition of the high-resistivity film. This prevents charge accumulation and avoids affecting the subsequent deposition of particles, thus preventing localized thinning and ensuring the uniformity of the high-resistivity film. Consequently, the uniformity of the constructed copper indium gallium selenide (CIGS) solar cell is improved.

[0016] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the structure of a flexible copper indium gallium selenide (CIGS) battery according to one embodiment of the present disclosure.

[0018] Figure 2 This is a schematic flowchart illustrating a method for fabricating a flexible copper indium gallium selenide (CIGS) battery according to one embodiment of this disclosure.

[0019] Figure 3 This is a schematic diagram showing the VOC results of electrical performance tests of a flexible copper indium gallium selenide battery according to one embodiment of the present disclosure, compared with Comparative Examples 2 and 3 and a blank control example.

[0020] Figure 4 This is a schematic diagram of the JSC results of electrical performance testing of a flexible copper indium gallium selenide (CIGS) battery according to one embodiment of the present disclosure, compared with Comparative Examples 2 and 3 and a blank control example.

[0021] Figure 5 This is a schematic diagram showing the FF results of electrical performance tests of a flexible copper indium gallium selenide (CIGS) battery according to one embodiment of the present disclosure, compared with Comparative Examples 2 and 3 and a blank control example.

[0022] Figure 6 This is a schematic diagram of the EFF results of electrical performance testing of a flexible copper indium gallium selenide (CIGS) battery according to one embodiment of the present disclosure, compared with Comparative Examples 2 and 3 and a blank control example.

[0023] Explanation of reference numerals in the attached figures 1. Substrate; 2. PN junction; 21. Back electrode film system; 22. Absorber layer; 23. Buffer layer; 3. Transparent conductive film; 4. High-resistivity thin film; 5. Transparent conductive front electrode; 6. Grid lines. Detailed Implementation

[0024] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0025] In this disclosure, unless otherwise stated, directional terms such as "upper" and "lower" are generally defined by the orientation of the accompanying drawings, and "inner" and "outer" refer to the inner and outer parts of the relevant components. Furthermore, terms such as "first" and "second" are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] In the description of this disclosure, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can be a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0027] With the development of photovoltaic cell technology, in order to obtain copper indium gallium selenide (CIGS) cells with better performance, the thickness of the high-resistivity layer is constantly decreasing. As the thickness of the high-resistivity layer decreases, the requirements for the uniformity of its thickness become increasingly stringent.

[0028] In related technologies, the high-resistivity layer of flexible copper indium gallium selenide (CIGS) solar cells is deposited on the surface of a PN junction. However, due to the non-conductivity of the high-resistivity layer itself, positive charges are generated during rapid deposition. These positive charges cannot pass through the PN junction and cannot move on its surface, leading to localized charge accumulation. This accumulated charge hinders the deposition of subsequent positively charged particles, affecting the deposition of these particles and causing localized thinning of the high-resistivity layer, resulting in uneven layer thickness. When the high-resistivity layer is unevenly thick, it may not effectively suppress photogenerated carrier recombination, leading to a decrease in localized cell efficiency, especially due to uneven efficiency distribution, which negatively impacts the performance of the resulting photovoltaic cell.

[0029] Therefore, such as Figure 1 As shown, one aspect of this disclosure provides a flexible copper indium gallium selenide (CIGS) solar cell, including a PN junction 2 and a composite window layer.

[0030] The composite window layer covers PN junction 2. In other words, the composite window layer covers the upper surface of PN junction 2.

[0031] The composite window layer includes a transparent conductive film 3 and a high-resistivity film 4. The transparent conductive film 3 covers the PN junction 2, and the high-resistivity film 4 covers the transparent conductive film 3. That is, the transparent conductive film 3 covers the upper surface of the PN junction 2, and the high-resistivity film 4 covers the upper surface of the transparent conductive film 3. The transparent conductive film 3 has good conductivity, and positive charges and free electrons can move freely in the transparent conductive film.

[0032] In the above technical solution, a transparent conductive film 3 is set between the high-resistivity film 4 and the PN junction 2. That is to say, the high-resistivity film 4 is deposited on the upper surface of the transparent conductive film 3 during the formation process. The conductivity of the transparent conductive film 3 allows positive charges and free electrons to move freely in the transparent conductive film. The freely moving positive charges and free electrons can combine and neutralize each other, thereby eliminating the charge generated by the high-resistivity film 4 during the deposition process, avoiding charge accumulation, and not affecting the subsequent deposition of particles. This also prevents the problem of local thinning, ensuring the uniformity of the high-resistivity film 4, and thus improving the uniformity of the constructed copper indium gallium selenide (CIGS) battery.

[0033] Optionally, in one embodiment of this disclosure, the transparent conductive film 3 includes an ITO film, an ICO film, or an AZO film. ITO, ICO, and AZO films have good conductivity, do not affect the optical path, and facilitate the movement of positive charges and free electrons within them, achieving neutralization, thereby further preventing charge accumulation on the high-resistivity film 4. In some examples, the transparent conductive film 3 is an ITO film. In other examples, the transparent conductive film 3 is an ICO film, or an AZO film.

[0034] Optionally, in one embodiment of this disclosure, the ITO thin film is prepared by magnetron sputtering using an ITO target doped with indium tin oxide, wherein the doping ratio of tin oxide is 2%-10% wt%. The preparation process using magnetron sputtering is convenient, similar to existing general processes in terms of equipment and procedures, facilitating adjustments to existing production lines and processes, and enabling easy promotion and large-scale production.

[0035] Optionally, in one embodiment of this disclosure, the ICO thin film is made by magnetron sputtering of ICO target material doped with indium cerium oxide. The doping ratio of cerium oxide is 2%-10%wt. The preparation by magnetron sputtering is easy to carry out, and the equipment and processes required are similar to those of existing general processes. It is convenient to adjust existing production lines and processes, and can be promoted with low difficulty, which is conducive to large-scale production.

[0036] Optionally, in one embodiment of this disclosure, the AZO thin film is prepared by magnetron sputtering using an AZO target doped with aluminum zinc oxide, wherein the doping ratio of aluminum oxide is 1%-3% wt%. The preparation process using magnetron sputtering is convenient, similar to existing general processes in terms of equipment and procedures, facilitating adjustments to existing production lines and processes, and enabling easy promotion and large-scale production.

[0037] Optionally, in one embodiment of this disclosure, the thickness of the transparent conductive film 3 is set to 5nm-50nm. Alternatively, the thickness of the transparent conductive film 3 is set to 10nm-30nm. This facilitates the movement of positive charges and free electrons within it, while avoiding excessive thickness of the transparent conductive film 3.

[0038] Optionally, in one embodiment of this disclosure, the resistivity of the transparent conductive film 3 is set to be less than 2E-3 Ω•cm. Optionally, the resistivity of the transparent conductive film 3 is set to be less than 5E-4 Ω•cm. This ensures the conductivity of the transparent conductive film, facilitating the movement of positive charges and free electrons within it.

[0039] Optionally, in one embodiment of this disclosure, the high-resistivity thin film 4 is configured as a ZnO thin film or a ZMO thin film. The ZnO thin film can be prepared using a ZnO target via magnetron sputtering. The ZMO thin film can be prepared using a ZMO target via magnetron sputtering.

[0040] Optionally, in one embodiment of this disclosure, the thickness of the high-resistivity film 4 is set to 5nm-45nm. Alternatively, the thickness of the high-resistivity film 4 is set to 5nm-30nm. This setting can improve the performance of the copper indium gallium selenide (CIGS) battery and enhance the overall efficiency of the flexible CIGS battery.

[0041] Optionally, in one embodiment of this disclosure, the PN junction 2 includes a back electrode film system 21, an absorption layer 22, and a buffer layer 23. The absorption layer 22 covers the back electrode film system 21, the buffer layer 23 covers the absorption layer 22, and a transparent conductive film 3 covers the buffer layer 23. The absorption layer 22 is configured as a copper indium gallium selenide (CIGS) absorption layer, and the buffer layer 23 is configured as a cadmium sulfide (CdS) buffer layer.

[0042] Optionally, in one embodiment of this disclosure, the flexible copper indium gallium selenide (CIGS) battery further includes a substrate 1, a transparent conductive front electrode 5, and a grid line 6.

[0043] The back electrode film 21 covers the substrate 1, and the transparent conductive front electrode 5 and the gate line 6 cover the high-resistivity thin film 4.

[0044] The substrate 1 is configured as a flexible metal substrate 1, which includes a stainless steel substrate 1, a Ti alloy substrate 1, or a single metal substrate 1. The flexible metal substrate 1 can be one of the following: a stainless steel substrate 1, a Ti alloy substrate 1, or a single metal substrate 1.

[0045] like Figure 2 As shown, a second aspect of this disclosure also provides a method for fabricating the above-mentioned flexible copper indium gallium selenide (CIGS) solar cell, comprising the following steps: Preparation of PN junction 2; A transparent conductive film 3 is coated on the PN junction 2 using a magnetron sputtering process; A high-resistivity film 4 is coated on the transparent conductive film 3 using a magnetron sputtering process.

[0046] Optionally, the preparation of PN junction 2 includes: Take flexible metal substrate 1 and clean it; A back electrode film system 21, a copper indium gallium selenide absorber layer 22, and a cadmium sulfide buffer layer 23 are sequentially fabricated on a flexible metal substrate 1 to obtain a PN junction 2.

[0047] Optionally, this preparation method further includes: A transparent conductive front electrode 5 and a gate line 6 are sequentially fabricated in a high-resistivity thin film 4.

[0048] Therefore, the overall process steps of this preparation method are as follows: S201. Take the flexible metal substrate 1 and clean it.

[0049] S202, a back electrode film system 21, a copper indium gallium selenide absorber layer 22, and a cadmium sulfide buffer layer 23 are sequentially prepared on a flexible metal substrate 1.

[0050] S203. A transparent conductive film 3 is coated on the PN junction 2 using a magnetron sputtering process.

[0051] S204. A high-resistivity film 4 is coated on the transparent conductive film 3 using a magnetron sputtering process.

[0052] S205. A transparent conductive front electrode 5 and a gate line 6 are sequentially fabricated on the surface of the high-resistivity thin film 4.

[0053] like Figures 3-6 As shown, this disclosure also provides a testing process for a flexible copper indium gallium selenide (CIGS) battery prepared using this method, along with two comparative examples and a blank control example.

[0054] The fabrication process of this flexible copper indium gallium selenide (CIGS) battery and the two comparative examples is as follows: The flexible Ti foil substrate 1 was cleaned, and Mo back electrode, copper indium gallium selenide absorber layer 22, and cadmium sulfide buffer layer 23 were sequentially fabricated on the 10cm x 10cm flexible Ti foil substrate 1.

[0055] The sample was cut into four 5cm x 5cm pieces. One piece was used in this example, one piece was used in comparative example 2, and one piece was used in comparative example 3.

[0056] In the first 5cm x 5cm sample, a transparent conductive film 3 was prepared on the cadmium sulfide buffer layer 23 by magnetron sputtering. The transparent conductive film 3 is an ITO film, using an ITO target with a tin oxide doping ratio of 5%wt. The thickness of the transparent conductive film 3 is about 10nm, and the resistivity is about 3E-4Ω•cm.

[0057] An oxide high-resistivity film 4, namely zinc oxide film i-ZnO, is prepared on the transparent conductive film 3 by magnetron sputtering. The thickness of the high-resistivity film 4 is about 18 nm.

[0058] A transparent conductive front electrode 5 and a grid line 6 are sequentially fabricated on an oxide high-resistivity thin film 4 to obtain a flexible copper indium gallium selenide battery, which is the example.

[0059] In the second 5cm x 5cm sample, an oxide high-resistivity film 4, namely zinc oxide film i-ZnO, was prepared on the cadmium sulfide buffer layer 23 by magnetron sputtering. The thickness of the high-resistivity film 4 was approximately 18nm.

[0060] A transparent conductive front electrode 5 and a gate line 6 were sequentially fabricated on an oxide high-resistivity thin film 4 to obtain Comparative Example 2.

[0061] In the third 5cm x 5cm sample, an oxide high-resistivity film 4, namely zinc oxide film i-ZnO, was prepared on the cadmium sulfide buffer layer 23 by magnetron sputtering. The high-resistivity film 4 was prepared using a zinc oxide target and the thickness of the high-resistivity film 4 was about 50nm. A transparent conductive front electrode 5 and a gate line 6 were sequentially fabricated on an oxide high-resistivity thin film 4 to obtain Comparative Example 3.

[0062] The obtained flexible copper indium gallium selenide (CIGS) solar cells, Comparative Example 2, Comparative Example 3, and the blank control group were all divided into 20 sections with an area of ​​0.501 cm² by scribe lines. 2 Small batteries were tested, and their electrical performance was assessed. The results are shown in Table 1 below. All electrical performance tests were conducted using an IV meter at a temperature of 25℃. A Newport 94023A simulator was used to simulate a solar irradiance source with an intensity of 1 kW / m². 2 Electrical performance testing was performed using a Keithley 2400 source meter.

[0063]

[0064] Table 1 Where VOC refers to open-circuit voltage, JSC refers to short-circuit current density, FF refers to fill factor, and EFF refers to efficiency.

[0065] By comparing with Comparative Examples 2 and 3, it can be found that, as a composite window layer, the introduction of transparent conductive film 3 has no significant impact on the open-circuit voltage of the battery. Transparent conductive film 3 will reduce the parallel resistance of the battery to a certain extent, resulting in a decrease in short-circuit current. However, due to the addition of transparent conductive film 3, the non-uniformity of battery electrical performance distribution caused by the introduction of high-resistivity film 4 can be improved while keeping the open-circuit voltage basically unchanged. This reduces carrier recombination loss, significantly improves the fill factor, and ultimately improves and optimizes battery efficiency.

[0066] The results of Comparative Examples 2 and 3 show that thinning the i-ZnO film has no significant effect on the open-circuit voltage of the battery, but significantly increases the short-circuit current. This is mainly because the thinning of i-ZnO reduces the series resistance within the battery. The fill factor decreases slightly because the uneven distribution of i-ZnO in some areas leads to carrier recombination losses in those areas, resulting in a lower fill factor. Ultimately, this translates to an improvement in the overall battery efficiency through i-ZnO thinning.

[0067] This demonstrates that the overall efficiency of this flexible copper indium gallium selenide (CIGS) battery is improved, while uniformity is ensured and yield is increased. Furthermore, the fabrication method of this flexible CIGS battery is similar to existing general processes in terms of equipment and procedures, facilitating adjustments to existing production lines and processes. It can be easily promoted and scaled up for mass production.

[0068] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0070] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A flexible copper indium gallium selenide (CIGS) battery, characterized in that, include: PN junction; A composite window layer covering the PN junction; The composite window layer comprises a transparent conductive film and a high-resistivity film, wherein the transparent conductive film covers the PN junction and the high-resistivity film covers the transparent conductive film.

2. The flexible copper indium gallium selenide battery according to claim 1, characterized in that, The transparent conductive film includes ITO film, ICO film or AZO film.

3. The flexible copper indium gallium selenide battery according to claim 2, characterized in that, The ITO thin film is fabricated using an ITO target doped with indium tin oxide via magnetron sputtering, with the tin oxide doping ratio being 2%-10% wt%. The ICO thin film is fabricated using an ICO target doped with indium cerium oxide via magnetron sputtering, with a cerium oxide doping ratio of 1%-5% wt%. The AZO thin film is made by magnetron sputtering of AZO target doped with aluminum zinc oxide. The doping ratio of aluminum oxide is 1%-3%wt.

4. The flexible copper indium gallium selenide battery according to claim 1, characterized in that, The thickness of the transparent conductive film is set to 5nm-50nm.

5. The flexible copper indium gallium selenide battery according to claim 1, characterized in that, The resistivity of the transparent conductive film is set to be less than 2E-3Ω•cm.

6. The flexible copper indium gallium selenide battery according to claim 1, characterized in that, The high-resistivity thin film is configured as a ZnO thin film or a ZMO thin film.

7. The flexible copper indium gallium selenide battery according to claim 1, characterized in that, The thickness of the high-resistivity film is set to 5nm-45nm.

8. The flexible copper indium gallium selenide (CIGS) battery according to any one of claims 1-7, characterized in that, The PN junction includes a back electrode film system, an absorption layer, and a buffer layer. The absorption layer covers the back electrode film system, the buffer layer covers the absorption layer, and the transparent conductive film covers the buffer layer.

9. The flexible copper indium gallium selenide battery according to claim 8, characterized in that, The flexible copper indium gallium selenide battery also includes a substrate, a transparent conductive front electrode, and grid lines; The back electrode film is covered on the substrate, and the transparent conductive front electrode and the gate line are covered on the high-resistivity thin film. The substrate is configured as a flexible metal substrate, which includes a stainless steel substrate, a Ti alloy substrate, or a single metal substrate.

10. A method for preparing a flexible copper indium gallium selenide (CIGS) battery as described in any one of claims 1-9, characterized in that, Includes the following steps: Preparation of PN junction; A transparent conductive film is coated on the PN junction using a magnetron sputtering process; A high-resistivity film is coated onto the transparent conductive film using a magnetron sputtering process.

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