A broadband gap CGSe flexible thin-film solar cell and a preparation method thereof

Abstract

The application provides a broadband gap CGSe flexible thin film solar cell and a preparation method thereof. The thin film solar cell comprises a flexible metal substrate layer, a back electrode layer, a CGSe absorption layer doped with sulfur and / or aluminum, a buffer layer, a window layer and a grid electrode. The preparation method of the thin film solar cell comprises the following steps: forming the back electrode layer on the flexible metal substrate layer by direct current magnetron sputtering; using a molecular beam epitaxy device, depositing the CGSe absorption layer by a three-step co-evaporation method while selectively doping aluminum, and selectively annealing in an S atmosphere to form the CGSe absorption layer doped with sulfur and / or aluminum; forming the buffer layer and then annealing; forming the window layer by radio frequency magnetron sputtering; and forming the grid electrode by electron beam evaporation to obtain the thin film solar cell. The broadband gap CGSe flexible thin film solar cell is suitable for being used as an underwater solar cell, and provides a high-efficiency power source for underwater vehicles, autonomous systems and the like.

Description

Technical Field

[0001] This invention belongs to the field of thin-film solar cell technology, specifically relating to a wide-bandgap CGSe flexible thin-film solar cell and its preparation method. Background Technology

[0002] Currently, non-renewable energy sources such as natural gas, coal, and oil are becoming increasingly scarce, and energy issues are increasingly becoming a bottleneck restricting economic development. Photovoltaic solar cells are expected to become a key solution to the energy problem. Driven by the huge potential of the photovoltaic market, solar cell manufacturers are investing heavily to expand production. Currently, solar cells have been proven to be a feasible technology for powering land-based and space-based equipment, and silicon-based solar panel technology dominates the market. However, there has been little development of directly using underwater solar cells to power marine systems.

[0003] The long-term operation of underwater vehicles, autonomous systems, and sensors requires a persistent power source, which is typically limited by reliance on shore-based power supplies, onboard batteries, or solar cells located on the surface or land. However, most attempts to power underwater systems with solar cells using materials with relatively narrow bandgap, such as silicon, have only achieved limited success. This is because water both scatters and absorbs visible light; a large portion of the red spectrum (600 nm) is absorbed in shallow water, while the blue to yellow portion (400-600 nm) is the last to be absorbed in deep water. Therefore, traditional solar cells using narrow-bandgap semiconductors are not suitable for deep-water applications. The maximum achievable efficiency of terrestrial solar cells is 34%; however, the maximum photoelectric conversion efficiency is limited when the irradiance spectrum narrows. Underwater spectroscopy necessitates the use of wider-bandgap semiconductors for underwater solar cells.

[0004] Second-generation solar cells, namely thin-film solar cells, such as copper indium gallium selenide (CIGS), are highly promising due to their flexibility in solar panel manufacturing and applicability to high-efficiency, low-cost tandem solar cells. CIGS thin-film solar cells also possess the significant advantage of tunable bandgap; by adjusting the Ga / (In+Ga) ratio, the bandgap can be varied between 1.02 eV and 1.68 eV. For narrow-gap CIGS thin-film solar cell devices with a 1.1 eV bandgap, such as Cu(In,Ga)Se2 (CIGSe) or Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells, the Ga / (In+Ga) ratio is as low as 0.3, and the technology is developing particularly rapidly, with multiple research institutions reporting efficiencies exceeding 22%. Currently, CIGSSe solar cells have achieved a world record efficiency of 23.35%. Meanwhile, Ga-based CuGaSe2 (CGSe), with an ideal wide bandgap of 1.68 eV, can serve as a semiconductor device for the absorption layer of a highly efficient tandem solar cell with a semi-transparent top layer. It is a single-junction solar cell capable of overcoming the Shockley-Queisse limit. However, the highest efficiency reported so far for CGSe single-junction devices is only 11.0%. When the gallium content increases, it is difficult to maintain good device performance. Improving the performance of CGSe thin-film solar cell devices has always been one of the research projects that many researchers have been striving to break through.

[0005] The main problem in CGSe devices is carrier recombination at the space charge region interface. As the gallium content increases, the recombination of charge carriers at the space charge region interface increases. Cu / Ga Cu ) and anion vacancies (V Se Defects can easily form defect states at deep bandgap locations, creating recombination centers and leading to performance degradation. Furthermore, with higher gallium content, the Fermi level at the CGSe absorber / buffer interface is closer to the middle of the bandgap; therefore, recombination near or at the interface becomes more pronounced as the CGSe bandgap increases. Additionally, the device suffers from high contact resistance between the back contact metal electrodes (e.g., Mo) and the CGSe absorber layer, and high contact resistance between the gate electrodes (e.g., Au, Ni) and the window layer. Despite these challenges, CGSe thin-film solar cells possess significant potential as underwater solar cells due to their wide bandgap semiconductor characteristics, which are well-suited to the wavelengths of underwater spectra.

[0006] Therefore, developing a novel wide-bandgap CGSe flexible thin-film solar cell has become one of the urgent problems to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a wide-bandgap CGSe flexible thin-film solar cell and its fabrication method. The thin-film solar cell of the present invention possesses characteristics such as flexibility and a wide bandgap, and can match the wavelength of the underwater spectrum, making it suitable as an underwater solar cell.

[0008] To achieve the above objectives, a first aspect of the present invention provides a wide-bandgap CGSe flexible thin-film solar cell, comprising:

[0009] Flexible metal substrate layer;

[0010] A back electrode layer is formed on the flexible metal substrate layer;

[0011] A CGSe absorber layer doped with sulfur (S) and / or aluminum (Al) is formed on the back electrode layer;

[0012] A buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer;

[0013] A window layer, which is formed on the buffer layer;

[0014] A gate electrode is formed on the window layer.

[0015] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the thickness of the flexible metal substrate layer is 0.03-0.05 mm. The flexible metal used is, for example, but not limited to, stainless steel, Ti, etc.

[0016] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the flexible metal substrate layer is obtained through the following steps: immersing the flexible metal in alcohol for 1-5 minutes; removing it and immersing it in concentrated hydrochloric acid solution for 1-5 minutes; removing it and immersing it in sodium hydroxide solution for 1-5 minutes; removing it and rinsing it with ultrapure water to remove residual solution; then immersing it in anhydrous ethanol for 1-5 minutes; and finally drying the surface of the flexible metal with high-purity nitrogen gas to obtain the flexible metal substrate layer. The dimensions of the flexible metal used are, for example, but not limited to, 10cm × 10cm. The concentrations of the alcohol, concentrated hydrochloric acid solution, and sodium hydroxide solution used can be conventionally adjusted by those skilled in the art.

[0017] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the material of the back electrode layer includes molybdenum (Mo).

[0018] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the thickness of the back electrode layer is 600-2000 nm.

[0019] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the back electrode layer is formed on the flexible metal substrate by DC magnetron sputtering. More specifically, the back electrode layer is formed on the flexible metal substrate by: placing the flexible metal substrate in a sputtering chamber, sputtering molybdenum under suitable vacuum and sputtering power conditions, first sputtering a first molybdenum layer with a thickness of 100-500 nm, and then sputtering a second molybdenum layer with a thickness of 500-1500 nm to form the back electrode layer. More preferably, the sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm². 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 In the formation of the back electrode layer, this invention employs a high-voltage, low-power sputtering process to deposit the first molybdenum layer, and a high-power, low-voltage sputtering process to deposit the second molybdenum layer. This approach ensures that the resulting back electrode layer has both good adhesion and meets the conductivity requirements.

[0020] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, based on the total number of atoms in the sulfur- and / or aluminum-doped CGSe absorber layer being 100%, it comprises 3-7% S atoms and / or Al atoms.

[0021] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, based on the total number of atoms in the CGSe absorber layer doped with sulfur and / or aluminum being 100%, it includes 0.1-1.0% Na atoms.

[0022] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the thickness of the CGSe absorber layer doped with sulfur and / or aluminum is 2.5-3.0 μm.

[0023] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the sulfur- and / or aluminum-doped CGSe absorber layer is formed on the back electrode layer by: depositing the CGSe absorber layer on the back electrode layer using a molecular beam epitaxy (MBE) device and selectively doping aluminum simultaneously using a three-step co-evaporation method, followed by selective annealing in an S atmosphere to form the sulfur- and / or aluminum-doped CGSe absorber layer. More specifically, the sulfur- and / or aluminum-doped CGSe absorber layer is formed on the back electrode layer by the following steps: In the vacuum chamber of a molecular beam epitaxy apparatus, firstly, Ga, Se, and NaF are co-evaporated, followed by Ga and Se co-evaporation to form Ga₂Se₃ on the back electrode layer, while simultaneously doping with Na to form a precursor layer; secondly, Cu and Se are co-evaporated, and Al is selectively co-evaporated, causing Cu to react with the precursor layer formed in the first co-evaporation step, and aluminum is selectively doped to form a Cu-rich and selectively aluminum-doped CGSe layer; thirdly, Ga and Se are co-evaporated to form the CGSe absorber layer; subsequently, selective annealing is performed in an S atmosphere to form the sulfur- and / or aluminum-doped CGSe absorber layer. More preferably, the temperature of the first co-evaporation step is 800-1100°C, and the time is 10-30 min; the temperature of the second co-evaporation step is 1100-1400°C, and the time is 10-20 min; the temperature of the third co-evaporation step is 800-1100°C, and the time is 10-30 min. In the first co-distillation step, the co-distillation time for Ga, Se, and NaF can be 5-15 min, followed by the co-distillation time for Ga and Se, which can also be 5-15 min. More preferably, the annealing temperature under S atmosphere is 150-300℃, and the time is 5-10 min.

[0024] This invention involves doping the wide-bandgap CGSe absorber with sulfur and aluminum, which expands its bandgap to 2.4 eV, further matching it with underwater spectra and thus improving the photoelectric conversion efficiency of underwater devices.

[0025] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the material of the buffer layer includes one or a combination of several of CdS, ZnS, Zn(S,O) and In2S3.

[0026] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the thickness of the buffer layer is 50-80 nm.

[0027] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by one or a combination of chemical bath deposition (CBD), atomic layer deposition (ALD), and magnetron sputtering. More specifically, the buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by: forming a CdS buffer layer using chemical bath deposition (CBD), and / or forming a buffer layer by one or a combination of ZnS, Zn(S,O), and In2S3 using atomic layer deposition (ALD) and / or radio frequency magnetron sputtering. The specific operational steps for forming the buffer layer using chemical bath deposition, atomic layer deposition, and radio frequency magnetron sputtering can all be performed according to conventional methods in the art, and this invention does not specifically limit them.

[0028] In the above-mentioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the buffer layer is annealed at a temperature of 120-180°C for 0-5 min (more preferably 1-5 min) in an air atmosphere.

[0029] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the material of the window layer includes intrinsic zinc oxide (i-ZnO) and / or aluminum-doped zinc oxide (AZO).

[0030] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the thickness of the window layer is 200-300 nm.

[0031] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the window layer has a double-layer structure, comprising an intrinsic zinc oxide layer and an aluminum-doped zinc oxide layer formed on the intrinsic zinc oxide layer. More preferably, the thickness of the intrinsic zinc oxide layer is 50 nm, and the thickness of the aluminum-doped zinc oxide layer is 200 nm.

[0032] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the window layer is formed on the buffer layer by radio frequency magnetron sputtering. More preferably, the sputtering vacuum of the sputtering window layer is 0.5-2.0 Pa, and the sputtering power is 1.0-3.0 W / cm². 2 .

[0033] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the gate electrode comprises a Ni / Al gate electrode. More preferably, the thickness of the nickel (Ni) in the gate electrode is 100-150 nm, and the thickness of the aluminum (Al) is 1000-10000 nm.

[0034] In the aforementioned wide-bandgap CGSe flexible thin-film solar cell, preferably, the gate electrode is formed on the window layer by electron beam evaporation.

[0035] A second aspect of the present invention provides a method for fabricating the above-mentioned wide-bandgap CGSe flexible thin-film solar cell, comprising the following steps:

[0036] (1) A back electrode layer is formed on a flexible metal substrate by DC magnetron sputtering;

[0037] (2) Using a molecular beam epitaxy (MBE) device, a three-step co-evaporation method is used to deposit a CGSe absorber layer on the back electrode layer while selectively doping with aluminum, and then selectively annealing in an S atmosphere to form a CGSe absorber layer doped with sulfur and / or aluminum.

[0038] (3) A buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by one or a combination of chemical bath deposition (CBD), atomic layer deposition (ALD) and magnetron sputtering, and then annealed to obtain an annealed buffer layer.

[0039] (4) A window layer is formed on the annealed buffer layer by radio frequency magnetron sputtering;

[0040] (5) A grid electrode is formed on the window layer by electron beam evaporation to obtain the wide-bandgap CGSe flexible thin-film solar cell.

[0041] In the above preparation method, preferably, the flexible metal substrate layer is obtained by the following steps: immersing the flexible metal in alcohol for 1-5 minutes; removing it and immersing it in concentrated hydrochloric acid solution for 1-5 minutes; removing it and immersing it in sodium hydroxide solution for 1-5 minutes; removing it and rinsing it with ultrapure water to remove residual solution; then immersing it in anhydrous ethanol for 1-5 minutes; and finally drying the surface of the flexible metal with high-purity nitrogen gas to obtain the flexible metal substrate layer. The size of the flexible metal used is, for example, but not limited to, 10cm × 10cm. The concentrations of the alcohol, concentrated hydrochloric acid solution, and sodium hydroxide solution used can be conventionally adjusted by those skilled in the art.

[0042] In the above preparation method, preferably, step (1) specifically includes: placing the flexible metal substrate layer into a sputtering chamber, sputtering molybdenum under suitable vacuum and sputtering power conditions, first sputtering a first molybdenum layer with a thickness of 100-500 nm, and then sputtering a second molybdenum layer with a thickness of 500-1500 nm to form the back electrode layer. More preferably, the sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm². 2The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 .

[0043] In the above preparation method, preferably, step (2) specifically includes: in the vacuum chamber of the molecular beam epitaxy equipment, firstly, Ga, Se and NaF are co-evaporated, then Ga and Se are co-evaporated to form Ga2Se3 on the back electrode layer, while Na is doped to form a precursor layer; secondly, Cu and Se are co-evaporated and Al is selectively co-evaporated, so that Cu reacts with the precursor layer formed in the first co-evaporation, and aluminum is selectively doped to form a CGSe layer with Cu-rich surface and selective aluminum doping; thirdly, Ga and Se are co-evaporated to form a CGSe absorber layer; then, selective annealing is performed in an S atmosphere to form the CGSe absorber layer doped with sulfur and / or aluminum. More preferably, the temperature of the first co-evaporation is 800-1100℃ and the time is 10-30 min; the temperature of the second co-evaporation is 1100-1400℃ and the time is 10-20 min; the temperature of the third co-evaporation is 800-1100℃ and the time is 10-30 min. In the first co-distillation step, the co-distillation time for Ga, Se, and NaF can be 5-15 min, followed by the co-distillation time for Ga and Se, which can also be 5-15 min. More preferably, the annealing temperature under S atmosphere is 150-300℃, and the time is 5-10 min.

[0044] In the above preparation method, preferably, step (3) specifically includes: forming a CdS buffer layer using chemical bath deposition (CBD), and / or forming a buffer layer of one or more combinations of ZnS, Zn(S,O) and In2S3 using atomic layer deposition (ALD) and / or radio frequency magnetron sputtering, and then annealing the buffer layer after annealing at a temperature of 120-180°C for 0-5 min (more preferably 1-5 min) in an air atmosphere.

[0045] In the above preparation method, preferably, in step (4), the sputtering vacuum degree of the sputtering window layer is 0.5-2.0 Pa, and the sputtering power is 1.0-3.0 W / cm². 2 .

[0046] This invention provides a wide-bandgap CGSe flexible thin-film solar cell and its fabrication method. Currently, narrow-bandgap materials used in land-based and space-based solar cells have limited applications in underwater solar cell development due to their poor matching with underwater spectra. Wide-bandgap materials, however, hold great potential for underwater solar cell development. This invention's technical solution involves depositing a copper gallium selenide (CGSe) thin-film absorber layer on a flexible metal substrate under high vacuum conditions, and then assembling a wide-bandgap CGSe flexible thin-film solar cell. Compared to traditional rigid substrates, flexible metal substrates offer advantages such as smaller size, portability, flexibility, high temperature resistance, and fewer impurities. They can withstand high temperatures during CGSe absorber layer deposition, improving absorber layer crystallinity while reducing the impact of impurities from the substrate diffusing into the absorber layer on device performance. Furthermore, this invention involves doping the wide-bandgap CGSe absorber layer with sulfur and aluminum, which expands its bandgap to 2.4 eV, further matching it with underwater spectra and thus improving the photoelectric conversion efficiency of underwater devices. Meanwhile, this invention employs one or more of CdS, ZnS, Zn(S,O), and In2S3 as a buffer layer to match the bandgap of the CGSe absorber layer with that of the buffer layer, thereby increasing the open-circuit voltage and improving device performance. The wide-bandgap CGSe flexible thin-film solar cell of this invention can adapt to a wider range of applications, especially underwater solar cells, providing a high-efficiency power source for underwater vehicles and autonomous systems, expanding the application areas of wide-bandgap, high-stability thin-film solar cells. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the wide-bandgap CGSe flexible thin-film solar cell provided in Examples 1 and 2.

[0048] Figure 2 This is a schematic diagram of the structure of the wide-bandgap CGSe flexible thin-film solar cell provided in Example 3.

[0049] Explanation of icon numbers:

[0050] 1-Flexible metal substrate layer; 2-Back electrode layer; 31-Sulfur-doped CGSe absorber layer; 32-Aluminum-doped CGSe absorber layer; 4-Buffer layer; 5-Window layer; 6-Gate electrode. Detailed Implementation

[0051] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0052] Example 1

[0053] This embodiment provides a wide-bandgap CGSe flexible thin-film solar cell, such as... Figure 1 As shown, it includes:

[0054] Flexible metal substrate layer 1;

[0055] Back electrode layer 2 is formed on the flexible metal substrate layer 1;

[0056] A sulfur-doped CGSe absorber layer 31 is formed on the back electrode layer 2;

[0057] Buffer layer 4 is formed on the sulfur-doped CGSe absorber layer 31;

[0058] Window layer 5, which is formed on the buffer layer 4;

[0059] The gate electrode 6 is formed on the window layer 5.

[0060] The flexible metal substrate 1 has a thickness of 0.03 mm. The flexible metal used is stainless steel.

[0061] The material of the back electrode layer 2 is molybdenum (Mo). The thickness of the back electrode layer 2 is 1300 nm.

[0062] The atomic ratio of Cu, Ga, and Se in the sulfur-doped CGSe absorber layer 31 is 1:1:2. Assuming the total number of atoms in the sulfur-doped CGSe absorber layer 31 is 100%, it includes 3% S atoms and 0.1% Na atoms. The thickness of the sulfur-doped CGSe absorber layer 31 is 2.5-3.0 μm.

[0063] The buffer layer 4 is made of CdS. The thickness of the buffer layer 4 is 50 nm. The buffer layer 4 has undergone annealing treatment at a temperature of 160°C for 2 minutes in an air atmosphere.

[0064] The window layer 5 has a double-layer structure, comprising an intrinsic zinc oxide (i-ZnO) layer and an aluminum-doped zinc oxide (AZO) layer formed on the intrinsic zinc oxide (i-ZnO) layer. The thickness of the intrinsic zinc oxide (i-ZnO) layer is 50 nm, and the thickness of the aluminum-doped zinc oxide (AZO) layer is 200 nm. The thickness of the window layer 5 is 250 nm.

[0065] The gate electrode 6 is a Ni / Al gate electrode. The thickness of the nickel (Ni) in the gate electrode 6 is 150 nm, and the thickness of the aluminum (Al) is 10000 nm.

[0066] The wide-bandgap CGSe flexible thin-film solar cell of this embodiment is prepared by the following steps:

[0067] (1) Select a flexible metal with a specification of 10cm×10cm, immerse it in alcohol for 3min; after taking it out, immerse it in concentrated hydrochloric acid solution for 3min; after taking it out, immerse it in sodium hydroxide solution for 3min; after taking it out, rinse it with a large amount of ultrapure water to remove residual solution; then immerse it in anhydrous ethanol for 3min; then use high-purity nitrogen to dry the surface of the flexible metal to obtain a clean and flat flexible metal substrate layer 1.

[0068] A clean, flat flexible metal substrate 1 is placed in the sputtering chamber of a DC magnetron sputtering equipment. Molybdenum is sputtered under suitable vacuum and sputtering power conditions. First, a first molybdenum layer with a thickness of 300 nm is sputtered, followed by a second molybdenum layer with a thickness of 1000 nm, forming the back electrode layer 2. The sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm². 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 ;

[0069] (2) Using a molecular beam epitaxy (MBE) apparatus, a three-step co-evaporation method is employed to deposit a CGSe absorber layer on the back electrode layer 2, followed by annealing in an S atmosphere to form a sulfur-doped CGSe absorber layer 31: In the vacuum chamber of the MBE apparatus, the first step involves co-evaporating Ga, Se, and NaF, followed by co-evaporating Ga and Se to form Ga₂Se₃ on the back electrode layer 2, while simultaneously doping with Na to form a precursor layer; the second step involves co-evaporating Cu and Se, allowing Cu to react with the precursor layer formed in the first step to form a Cu-rich CGSe layer; the third step involves co-evaporating Ga and Se to form the CGSe absorber layer; Then, annealing is performed in an S atmosphere at a temperature of 150-300℃ for 5-10 minutes to form a sulfur-doped CGSe absorber layer 31. Specifically, the first co-evaporation step is performed at a temperature of 800-1100℃ for 10-30 minutes, during which Ga, Se, and NaF are co-evaporated for 5-15 minutes, followed by Ga and Se co-evaporation for another 5-15 minutes. The second co-evaporation step is performed at a temperature of 1100-1300℃ for 10-20 minutes. The third co-evaporation step is performed at a temperature of 800-1100℃ for 10-30 minutes.

[0070] (3) A buffer layer 4 is formed on the sulfur-doped CGSe absorber layer 31 by chemical bath deposition (CBD). Then, the surface is cleaned with ultrapure water and the residual moisture on the surface is dried with high-purity nitrogen. After that, it is annealed in a drying oven at a temperature of 160°C for 2 minutes in an air atmosphere to obtain the annealed buffer layer 4.

[0071] (4) Intrinsic ZnO was prepared using an intrinsic ZnO target (99.99% purity), and AZO was prepared using a ZnO:Al2O3 target (doped with 2wt% Al2O3). An intrinsic zinc oxide (i-ZnO) layer with a thickness of 50 nm and an aluminum-doped zinc oxide (AZO) layer with a thickness of 200 nm were sequentially sputtered onto the annealed buffer layer 4 using an RF magnetron sputtering apparatus. The sputtering vacuum was 0.5-2.0 Pa, and the sputtering power was 1.0-3.0 W / cm². 2 This forms window layer 5;

[0072] (5) Flatten the gate electrode mask onto the surface of window layer 5 and place it in the vacuum chamber of the electron beam evaporation coating equipment. By adjusting the beam position and electron beam current, evaporate the Ni and Al metal sources placed in the crucible at high temperature, and deposit Ni and Al electrodes sequentially. The thickness of the Ni electrode is [missing information]. The thickness of the Al electrode is A grid electrode 6 is formed to obtain the wide-bandgap CGSe flexible thin-film solar cell.

[0073] Example 2

[0074] This embodiment provides a wide-bandgap CGSe flexible thin-film solar cell, such as... Figure 1 As shown, it includes:

[0075] Flexible metal substrate layer 1;

[0076] Back electrode layer 2 is formed on the flexible metal substrate layer 1;

[0077] A sulfur-doped CGSe absorber layer 31 is formed on the back electrode layer 2;

[0078] Buffer layer 4 is formed on the sulfur-doped CGSe absorber layer 31;

[0079] Window layer 5, which is formed on the buffer layer 4;

[0080] The gate electrode 6 is formed on the window layer 5.

[0081] The flexible metal substrate 1 has a thickness of 0.03 mm. The flexible metal used is stainless steel.

[0082] The material of the back electrode layer 2 is molybdenum (Mo). The thickness of the back electrode layer 2 is 1300 nm.

[0083] The atomic ratio of Cu, Ga, and Se in the sulfur-doped CGSe absorber layer 31 is 1:1:2. Assuming the total number of atoms in the sulfur-doped CGSe absorber layer 31 is 100%, it includes 3% S atoms and 0.5% Na atoms. The thickness of the sulfur-doped CGSe absorber layer 31 is 2.5-3.0 μm.

[0084] The buffer layer 4 is made of ZnS. The thickness of the buffer layer 4 is 50 nm. The buffer layer 4 has undergone annealing treatment at a temperature of 160°C for 2 minutes in an air atmosphere.

[0085] The window layer 5 has a double-layer structure, comprising an intrinsic zinc oxide (i-ZnO) layer and an aluminum-doped zinc oxide (AZO) layer formed on the intrinsic zinc oxide (i-ZnO) layer. The thickness of the intrinsic zinc oxide (i-ZnO) layer is 50 nm, and the thickness of the aluminum-doped zinc oxide (AZO) layer is 200 nm. The thickness of the window layer 5 is 250 nm.

[0086] The gate electrode 6 is a Ni / Al gate electrode. The thickness of the nickel (Ni) in the gate electrode 6 is 150 nm, and the thickness of the aluminum (Al) is 10000 nm.

[0087] The wide-bandgap CGSe flexible thin-film solar cell of this embodiment is prepared by the following steps:

[0088] (1) Select a flexible metal with a specification of 10cm×10cm, immerse it in alcohol for 3min; after taking it out, immerse it in concentrated hydrochloric acid solution for 3min; after taking it out, immerse it in sodium hydroxide solution for 3min; after taking it out, rinse it with a large amount of ultrapure water to remove residual solution; then immerse it in anhydrous ethanol for 3min; then use high-purity nitrogen to dry the surface of the flexible metal to obtain a clean and flat flexible metal substrate layer 1.

[0089] A clean, flat flexible metal substrate 1 is placed in the sputtering chamber of a DC magnetron sputtering equipment. Molybdenum is sputtered under suitable vacuum and sputtering power conditions. First, a first molybdenum layer with a thickness of 300 nm is sputtered, followed by a second molybdenum layer with a thickness of 1000 nm, forming the back electrode layer 2. The sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm². 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 ;

[0090] (2) Using a molecular beam epitaxy (MBE) apparatus, a three-step co-evaporation method is employed to deposit a CGSe absorber layer on the back electrode layer 2, followed by annealing in an S atmosphere to form a sulfur-doped CGSe absorber layer 31: In the vacuum chamber of the MBE apparatus, the first step involves co-evaporating Ga, Se, and NaF, followed by co-evaporating Ga and Se to form Ga₂Se₃ on the back electrode layer 2, while simultaneously doping with Na to form a precursor layer; the second step involves co-evaporating Cu and Se, allowing Cu to react with the precursor layer formed in the first step to form a Cu-rich CGSe layer; the third step involves co-evaporating Ga and Se to form the CGSe absorber layer; Then, annealing is performed in an S atmosphere at a temperature of 150-300℃ for 5-10 minutes to form a sulfur-doped CGSe absorber layer 31. The first co-evaporation step is performed at a temperature of 800-1100℃ for 10-30 minutes, during which Ga, Se, and NaF are co-evaporated for 5-15 minutes, followed by Ga and Se co-evaporation for 5-15 minutes. The second co-evaporation step is performed at a temperature of 1100-1300℃ for 10-20 minutes. The third co-evaporation step is performed at a temperature of 800-1100℃ for 10-30 minutes.

[0091] (3) A buffer layer 4 is formed on the sulfur-doped CGSe absorber layer 31 by atomic deposition (ALD), then the surface is cleaned with ultrapure water, and then the residual moisture on the surface is dried with high-purity nitrogen. After that, it is annealed in a drying oven at a temperature of 160°C for 2 minutes in an air atmosphere to obtain the annealed buffer layer 4.

[0092] (4) Intrinsic ZnO was prepared using an intrinsic ZnO target (99.99% purity), and AZO was prepared using a ZnO:Al2O3 target (doped with 2wt% Al2O3). An intrinsic zinc oxide (i-ZnO) layer with a thickness of 50 nm and an aluminum-doped zinc oxide (AZO) layer with a thickness of 200 nm were sequentially sputtered onto the annealed buffer layer 4 using an RF magnetron sputtering apparatus. The sputtering vacuum was 0.5-2.0 Pa, and the sputtering power was 1.0-3.0 W / cm². 2 This forms window layer 5;

[0093] (5) Flatten the gate electrode mask onto the surface of window layer 5 and place it in the vacuum chamber of the electron beam evaporation coating equipment. By adjusting the beam position and electron beam current, evaporate the Ni and Al metal sources placed in the crucible at high temperature, and deposit Ni and Al electrodes sequentially. The thickness of the Ni electrode is [missing information]. The thickness of the Al electrode is A grid electrode 6 is formed to obtain the wide-bandgap CGSe flexible thin-film solar cell.

[0094] Example 3

[0095] This embodiment provides a wide-bandgap CGSe flexible thin-film solar cell, such as... Figure 2 As shown, it includes:

[0096] Flexible metal substrate layer 1;

[0097] Back electrode layer 2 is formed on the flexible metal substrate layer 1;

[0098] An aluminum-doped CGSe absorber layer 32 is formed on the back electrode layer 2;

[0099] Buffer layer 4 is formed on the aluminum-doped CGSe absorber layer 32;

[0100] Window layer 5, which is formed on the buffer layer 4;

[0101] The gate electrode 6 is formed on the window layer 5.

[0102] The flexible metal substrate 1 has a thickness of 0.03 mm. The flexible metal used is stainless steel.

[0103] The material of the back electrode layer 2 is molybdenum (Mo). The thickness of the back electrode layer 2 is 1300 nm.

[0104] The atomic ratio of Cu, Ga, and Se in the aluminum-doped CGSe absorber layer 32 is 1:1:2. Assuming the total number of atoms in the aluminum-doped CGSe absorber layer 32 is 100%, it includes 5% Al atoms and 1% Na atoms. The thickness of the aluminum-doped CGSe absorber layer 32 is 2.5-3.0 μm.

[0105] The material of the buffer layer 4 is In2S3. The thickness of the buffer layer 4 is 50 nm. The buffer layer 4 has undergone annealing treatment at a temperature of 160°C for 2 minutes in an air atmosphere.

[0106] The window layer 5 has a double-layer structure, comprising an intrinsic zinc oxide (i-ZnO) layer and an aluminum-doped zinc oxide (AZO) layer formed on the intrinsic zinc oxide (i-ZnO) layer. The thickness of the intrinsic zinc oxide (i-ZnO) layer is 50 nm, and the thickness of the aluminum-doped zinc oxide (AZO) layer is 200 nm. The thickness of the window layer 5 is 250 nm.

[0107] The gate electrode 6 is a Ni / Al gate electrode. The thickness of the nickel (Ni) in the gate electrode 6 is 150 nm, and the thickness of the aluminum (Al) is 10000 nm.

[0108] The wide-bandgap CGSe flexible thin-film solar cell of this embodiment is prepared by the following steps:

[0109] (1) Select a flexible metal with a specification of 10cm×10cm, immerse it in alcohol for 3min; after taking it out, immerse it in concentrated hydrochloric acid solution for 3min; after taking it out, immerse it in sodium hydroxide solution for 3min; after taking it out, rinse it with a large amount of ultrapure water to remove residual solution; then immerse it in anhydrous ethanol for 3min; then use high-purity nitrogen to dry the surface of the flexible metal to obtain a clean and flat flexible metal substrate layer 1.

[0110] A clean, flat flexible metal substrate 1 is placed in the sputtering chamber of a DC magnetron sputtering equipment. Molybdenum is sputtered under suitable vacuum and sputtering power conditions. First, a first molybdenum layer with a thickness of 300 nm is sputtered, followed by a second molybdenum layer with a thickness of 1000 nm, forming the back electrode layer 2. The sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm². 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 ;

[0111] (2) Using a molecular beam epitaxy (MBE) apparatus, a three-step co-evaporation method is employed to deposit a CGSe absorber layer on the back electrode layer 2 while simultaneously doping with aluminum, forming an aluminum-doped CGSe absorber layer 32: In the vacuum chamber of the MBE apparatus, in the first step, Ga, Se, and NaF are co-evaporated, followed by Ga and Se co-evaporation to form Ga2Se3 on the back electrode layer 2, while simultaneously doping with Na to form a precursor layer; in the second step, Cu, Se, and Al are co-evaporated, allowing Cu to react with the precursor layer formed in the first step, and aluminum is doped to form a Cu-rich and aluminum-doped CGSe layer; in the third step... The process involves three steps of co-evaporation of Ga and Se to form a CGSe absorber layer, which in turn forms an aluminum-doped CGSe absorber layer 32. The first step involves co-evaporation at 800-1100℃ for 10-30 minutes, with Ga, Se, and NaF co-evaporated for 5-15 minutes, followed by Ga and Se co-evaporation for another 5-15 minutes. The second step involves co-evaporation at 1100-1300℃ for 10-20 minutes. The third step involves co-evaporation at 800-1100℃ for 10-30 minutes.

[0112] (3) A buffer layer 4 is formed on the aluminum-doped CGSe absorber layer 32 by atomic deposition (ALD), then the surface is cleaned with ultrapure water, and then the residual moisture on the surface is dried with high-purity nitrogen. After that, it is annealed in a drying oven at a temperature of 160°C for 2 minutes in an air atmosphere to obtain the annealed buffer layer 4.

[0113] (4) Intrinsic ZnO was prepared using an intrinsic ZnO target (99.99% purity), and AZO was prepared using a ZnO:Al2O3 target (doped with 2wt% Al2O3). An intrinsic zinc oxide (i-ZnO) layer with a thickness of 50 nm and an aluminum-doped zinc oxide (AZO) layer with a thickness of 200 nm were sequentially sputtered onto the annealed buffer layer 4 using an RF magnetron sputtering apparatus. The sputtering vacuum was 0.5-2.0 Pa, and the sputtering power was 1.0-3.0 W / cm². 2 This forms window layer 5;

[0114] (5) Flatten the gate electrode mask onto the surface of window layer 5 and place it in the vacuum chamber of the electron beam evaporation coating equipment. By adjusting the beam position and electron beam current, evaporate the Ni and Al metal sources placed in the crucible at high temperature, and deposit Ni and Al electrodes sequentially. The thickness of the Ni electrode is [missing information]. The thickness of the Al electrode is A grid electrode 6 is formed to obtain the wide-bandgap CGSe flexible thin-film solar cell.

Claims

1. A wide-bandgap CGSe flexible thin-film solar cell, comprising: Flexible metal substrate layer; A back electrode layer is formed on the flexible metal substrate layer; A CGSe absorber layer doped with sulfur and / or aluminum is formed on the back electrode layer; A buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer; A window layer, which is formed on the buffer layer; A gate electrode is formed on the window layer; The total number of atoms in the sulfur- and / or aluminum-doped CGSe absorber layer is 100%, which includes 3-7% S atoms and / or Al atoms, and 0.1-1.0% Na atoms. The sulfur- and / or aluminum-doped CGSe absorber layer is formed on the back electrode layer by the following steps: In the vacuum chamber of a molecular beam epitaxy apparatus, firstly, Ga, Se, and NaF are co-evaporated, followed by Ga and Se co-evaporation to form Ga2Se3 on the back electrode layer, while simultaneously doping with Na to form a precursor layer; secondly, Cu and Se are co-evaporated, and Al is selectively co-evaporated, causing Cu to react with the precursor layer formed in the first co-evaporation step, and aluminum is selectively doped to form a Cu-rich and selectively aluminum-doped CGSe layer; thirdly, Ga and Se are co-evaporated to form the CGSe absorber layer; subsequently, selective annealing is performed in an S atmosphere to form the sulfur- and / or aluminum-doped CGSe absorber layer.

2. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The thickness of the flexible metal substrate is 0.03-0.05 mm.

3. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The flexible metal substrate is obtained by the following steps: immersing the flexible metal in alcohol for 1-5 minutes; removing it and immersing it in concentrated hydrochloric acid solution for 1-5 minutes; removing it and immersing it in sodium hydroxide solution for 1-5 minutes; removing it and rinsing it with ultrapure water to remove residual solution; then immersing it in anhydrous ethanol for 1-5 minutes; and finally drying the surface of the flexible metal with high-purity nitrogen gas to obtain the flexible metal substrate.

4. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The material of the back electrode layer includes molybdenum.

5. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The thickness of the back electrode layer is 600-2000 nm.

6. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The back electrode layer is formed on the flexible metal substrate layer by DC magnetron sputtering.

7. The wide-bandgap CGSe flexible thin-film solar cell according to claim 6, wherein, The back electrode layer is formed on the flexible metal substrate layer by the following method: placing the flexible metal substrate layer in a sputtering chamber, sputtering molybdenum under appropriate vacuum and sputtering power conditions, first sputtering a first molybdenum layer with a thickness of 100-500 nm, and then sputtering a second molybdenum layer with a thickness of 500-1500 nm to form the back electrode layer.

8. The wide-bandgap CGSe flexible thin-film solar cell according to claim 7, wherein, The sputtering vacuum for the first molybdenum layer was 2.0-3.0 Pa, and the sputtering power was 0.5-2 W / cm². 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 .

9. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The thickness of the sulfur- and / or aluminum-doped CGSe absorber layer is 2.5-3.0 μm.

10. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, In the formation of the CGSe absorber layer doped with sulfur and / or aluminum, the temperature of the first co-evaporation step is 800-1100℃ and the time is 10-30 min; the temperature of the second co-evaporation step is 1100-1400℃ and the time is 10-20 min; and the temperature of the third co-evaporation step is 800-1100℃ and the time is 10-30 min.

11. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, During the formation of the sulfur- and / or aluminum-doped CGSe absorber layer, the annealing temperature under an S atmosphere is 150-300°C for 5-10 minutes.

12. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The material of the buffer layer includes one or a combination of several of CdS, ZnS, Zn(S,O) and In2S3.

13. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The thickness of the buffer layer is 50-80 nm.

14. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by one or more of chemical bath deposition, atomic layer deposition and magnetron sputtering.

15. The wide-bandgap CGSe flexible thin-film solar cell according to claim 14, wherein, The buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by: forming a CdS buffer layer using chemical bath deposition, and / or forming a buffer layer using atomic layer deposition and / or radio frequency magnetron sputtering, forming a combination of one or more of ZnS, Zn(S,O) and In2S3.

16. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The buffer layer is annealed at a temperature of 120-180°C for 0-5 minutes in an air atmosphere.

17. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The window layer is made of intrinsic zinc oxide and / or aluminum-doped zinc oxide.

18. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The thickness of the window layer is 200-300 nm.

19. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The window layer has a double-layer structure, comprising an intrinsic zinc oxide layer and an aluminum-doped zinc oxide layer formed on the intrinsic zinc oxide layer.

20. The wide-bandgap CGSe flexible thin-film solar cell according to claim 19, wherein, The thickness of the intrinsic zinc oxide layer is 50 nm, and the thickness of the aluminum-doped zinc oxide layer is 200 nm.

21. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The window layer is formed on the buffer layer by radio frequency magnetron sputtering.

22. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The gate electrode includes a Ni / Al gate electrode.

23. The wide-bandgap CGSe flexible thin-film solar cell according to claim 22, wherein, The thickness of nickel in the gate electrode is 100-150 nm, and the thickness of aluminum is 1000-10000 nm.

24. The wide-bandgap CGSe flexible thin-film solar cell according to claim 1, wherein, The gate electrode is formed on the window layer by electron beam evaporation.

25. A method for preparing a wide-bandgap CGSe flexible thin-film solar cell according to any one of claims 1-24, comprising the following steps: (1) A back electrode layer is formed on a flexible metal substrate by DC magnetron sputtering; (2) In the vacuum chamber of the molecular beam epitaxy equipment, the first step is to co-evaporate Ga, Se and NaF, then co-evaporate Ga and Se to form Ga2Se3 on the back electrode layer, while doping Na to form a precursor layer; the second step is to co-evaporate Cu and Se and selectively co-evaporate Al, so that Cu reacts with the precursor layer formed in the first step, and selectively doping aluminum to form a CGSe layer with Cu-rich surface and selective aluminum doping; the third step is to co-evaporate Ga and Se to form a CGSe absorber layer; then selectively annealing is performed in an S atmosphere to form the CGSe absorber layer doped with sulfur and / or aluminum. (3) A buffer layer is formed on the sulfur- and / or aluminum-doped CGSe absorber layer by one or more of chemical bath deposition, atomic layer deposition and magnetron sputtering, and then annealed to obtain an annealed buffer layer. (4) A window layer is formed on the annealed buffer layer by radio frequency magnetron sputtering; (5) A grid electrode is formed on the window layer by electron beam evaporation to obtain the wide-bandgap CGSe flexible thin-film solar cell.

26. The preparation method according to claim 25, wherein, Step (1) specifically includes: placing the flexible metal substrate layer into the sputtering chamber, sputtering molybdenum under appropriate vacuum and sputtering power conditions, first sputtering a first molybdenum layer with a thickness of 100-500nm, and then sputtering a second molybdenum layer with a thickness of 500-1500nm to form the back electrode layer.

27. The preparation method according to claim 26, wherein, In step (1), the sputtering vacuum degree for sputtering the first molybdenum layer is 2.0-3.0 Pa, and the sputtering power is 0.5-2 W / cm. 2 The sputtering vacuum degree for sputtering the second molybdenum layer was 0.1-0.5 Pa, and the sputtering power was 4-6 W / cm². 2 .

28. The preparation method according to claim 25, wherein, In step (2), the temperature of the first co-steaming step is 800-1100℃ and the time is 10-30min; the temperature of the second co-steaming step is 1100-1400℃ and the time is 10-20min; the temperature of the third co-steaming step is 800-1100℃ and the time is 10-30min.

29. The preparation method according to claim 25, wherein, In step (2), the annealing temperature under S atmosphere is 150-300℃ and the time is 5-10min.

30. The preparation method according to claim 25, wherein, Step (3) specifically includes: forming a CdS buffer layer using chemical bath deposition, and / or forming a buffer layer using atomic layer deposition and / or radio frequency magnetron sputtering, which is one or a combination of ZnS, Zn(S,O) and In2S3, and then annealing the buffer layer at a temperature of 120-180°C for 0-5 min in an air atmosphere to obtain the annealed buffer layer.

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