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CN-116230791-B - Wide-band gap CGSe flexible thin-film solar cell and preparation method thereof

CN116230791BCN 116230791 BCN116230791 BCN 116230791BCN-116230791-B

Abstract

The invention provides a wide-band 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 gate electrode. The preparation method of the thin film solar cell comprises the steps of forming a back electrode layer on a flexible metal substrate layer through direct current magnetron sputtering, depositing CGSe an absorption layer by adopting a three-step co-evaporation method by utilizing molecular beam epitaxy equipment, simultaneously selectively doping aluminum, selectively annealing in S atmosphere to form a CGSe absorption layer doped with sulfur and/or aluminum, forming a buffer layer, then annealing, forming a window layer through radio frequency magnetron sputtering, and forming a gate electrode through electron beam evaporation to obtain the thin film solar cell. The wide-band gap CGSe flexible thin-film solar cell is suitable to be used as an underwater solar cell, and provides a high-efficiency power source for underwater vehicles, autonomous systems and the like.

Inventors

  • WANG LEI
  • YANG CHUNLEI
  • LI WEIMIN
  • TANG WEI
  • YU SHEN
  • YUAN XINYE
  • LI SONG
  • WANG SAIQIANG
  • MA MING
  • Ning De

Assignees

  • 中国科学院深圳先进技术研究院

Dates

Publication Date
20260512
Application Date
20230320

Claims (20)

  1. 1. A wide bandgap CGSe flexible thin film solar cell, comprising: a flexible metal substrate layer; a back electrode layer formed on the flexible metal substrate layer; a CGSe absorber layer doped with sulfur and/or aluminum formed on the back electrode layer; A buffer layer formed on the CGSe absorption layer doped with sulfur and/or aluminum; a window layer formed on the buffer layer; A gate electrode formed on the window layer; Wherein the total atomic number in the CGSe absorption layer doped with sulfur and/or aluminum is 100%, and the absorption layer comprises 3-7% of S atoms and/or Al atoms and 0.1-1.0% of Na atoms; The CGSe absorption layer doped with sulfur and/or aluminum is formed on the back electrode layer by co-evaporating Ga, se and NaF in a vacuum chamber of a molecular beam epitaxy device, forming Ga 2 Se 3 on the back electrode layer by co-evaporating Ga, se and Na, doping Na to form a precursor layer, co-evaporating Cu, se and optionally Al in a second step, reacting Cu with the precursor layer formed by the co-evaporation in the first step, optionally doping aluminum to form a CGSe layer with a Cu-rich surface and optionally doped with aluminum, co-evaporating Ga and Se in a third step to form a CGSe absorption layer, and optionally annealing in an S atmosphere to form the CGSe absorption layer doped with sulfur and/or aluminum.
  2. 2. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the thickness of the flexible metal substrate layer is 0.03-0.05mm.
  3. 3. The wide-band gap CGSe flexible thin-film solar cell according to claim 1, wherein the flexible metal substrate layer is obtained by immersing the flexible metal in alcohol for 1-5min, immersing in concentrated hydrochloric acid solution for 1-5min after taking out, immersing in sodium hydroxide solution for 1-5min after taking out, rinsing with ultrapure water to remove residual solution after taking out, immersing in absolute ethyl alcohol for 1-5min, and drying the surface of the flexible metal by using high-purity nitrogen gas to obtain the flexible metal substrate layer.
  4. 4. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the material of the back electrode layer comprises molybdenum.
  5. 5. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the thickness of the back electrode layer is 600-2000nm.
  6. 6. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the back electrode layer is formed on the flexible metal substrate layer by dc magnetron sputtering.
  7. 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 placing the flexible metal substrate layer into a sputtering chamber, sputtering molybdenum under suitable vacuum, sputtering power conditions, first a first molybdenum layer having a thickness of 100-500nm, and then a second molybdenum layer having a thickness of 500-1500nm, forming the back electrode layer.
  8. 8. The wide bandgap CGSe flexible thin-film solar cell of claim 7, wherein the sputter vacuum for sputtering the first molybdenum layer is 2.0-3.0Pa, the sputter power is 0.5-2W/cm 2 , the sputter vacuum for sputtering the second molybdenum layer is 0.1-0.5Pa, the sputter power is 4-6W/cm 2 .
  9. 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. 10. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein during formation of the CGSe absorber layer doped with sulfur and/or aluminum, the first co-evaporation step is at 800-1100 ℃ for 10-30min, the second co-evaporation step is at 1100-1400 ℃ for 10-20min, and the third co-evaporation step is at 800-1100 ℃ for 10-30min.
  11. 11. The wide bandgap CGSe flexible thin-film solar cell according to claim 1, wherein during the formation of the CGSe absorber layer doped with sulfur and/or aluminum, annealing is performed at a temperature of 150-300 ℃ for a time of 5-10min under S atmosphere.
  12. 12. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the material of the buffer layer comprises one or a combination of several of CdS, znS, zn (S, O) and In 2 S 3 .
  13. 13. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the thickness of the buffer layer is 50-80nm.
  14. 14. The wide bandgap CGSe flexible thin-film solar cell as claimed in claim 1, wherein the buffer layer is formed on the sulfur and/or aluminum doped CGSe absorber layer by one or a combination of chemical water bath deposition, atomic layer deposition and magnetron sputtering.
  15. 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 water bath deposition and/or forming a buffer layer of one or a combination of ZnS, zn (S, O) and In 2 S 3 using atomic layer deposition and/or radio frequency magnetron sputtering.
  16. 16. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the buffer layer is annealed at a temperature of 120-180 ℃ for a time of 0-5min with air atmosphere.
  17. 17. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the material of the window layer comprises intrinsic zinc oxide and/or aluminum doped zinc oxide.
  18. 18. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the window layer has a thickness of 200-300nm.
  19. 19. The wide bandgap CGSe flexible thin-film solar cell of claim 1, wherein the window layer is a bilayer structure comprising an intrinsic zinc oxide layer and an aluminum doped zinc oxide layer formed on the intrinsic zinc oxide layer.
  20. 20. The wide bandgap CGSe flexible thin-film solar cell of claim 19, wherein the intrinsic zinc oxide layer has a thickness of 50nm and the aluminum doped zinc oxide layer has a thickness of 200nm.

Description

Wide-band gap CGSe flexible thin-film solar cell and preparation method thereof Technical Field The invention belongs to the technical field of thin-film solar cells, and particularly relates to a wide-band gap CGSe flexible thin-film solar cell and a preparation method thereof. Background Currently, non-renewable energy sources such as natural gas, coal, petroleum and the like are gradually deficient, and the energy problem becomes a bottleneck for restricting economic development increasingly. Photovoltaic solar cells are expected to become a key to solving the energy problem. Under the promotion of the huge potential of the photovoltaic market, the solar cell manufacturing industry strives for huge investment and expands production. Solar cells have now proven to be a viable technology for powering land-based and space-based devices, with silicon-based solar panel technology dominating the market, but the direct use of solar cells under water for powering marine systems has not been much developed. Long-term operation of underwater vehicles, autonomous systems and sensors requires a long-lasting power supply, often relying on an onshore power supply, an on-board battery or solar cells located on water or land for power, is severely limited. However, with materials such as silicon having a relatively narrow band gap, most of the attempts to power underwater systems using solar cells have met with limited success. This is because water can scatter and absorb visible light, a large amount of red (600 nm) in the solar spectrum is absorbed at shallow water, and blue to yellow (400-600 nm) in the spectrum is the last absorbed part at deep water, so conventional solar cells using narrow band gap semiconductors are not suitable for deep water applications. The maximum obtainable efficiency of terrestrial solar cells is 34%, however, when the irradiation spectrum is narrowed, the maximum photoelectric conversion efficiency is limited, and the underwater spectrum is more inclined to use a wider band gap semiconductor for underwater solar cells. The second generation solar cells, i.e. thin film solar cells, such as copper indium gallium diselenide (CIGS), have great development prospects due to the flexibility of manufacturing solar panels and the applicability of high-efficiency, low-cost tandem solar cells. Meanwhile, the CIGS thin film solar cell has the important advantage that the band gap of the CIGS thin film solar cell is adjustable, and the band gap can be changed between 1.02eV and 1.68eV by adjusting the ratio of Ga/(in+Ga). For 1.1eV narrow gap CIGS thin film solar cell devices, such as Cu (In, ga) Se 2 (CIGSe) or Cu (In, ga) (S, se) 2 (CIGSSe) solar cells, the Ga/(in+ga) ratio is as low as 0.3, the technological development is particularly rapid, and the efficiency reported by multiple research institutions exceeds 22%. Currently, CIGSSe solar cells reach 23.35% of world records in efficiency. While the ideal wide bandgap 1.68eV Ga-based CuGaSe 2 (CGSe) can be used as a semiconductor device for efficient tandem solar semitransparent top cell absorber layers, which is a single junction solar cell capable of overcoming the schokli-queter limit (the Shockley-Queisse limit). However, the highest efficiency of CGSe single junction devices reported so far is only 11.0%, and when the gallium content is increased, it is difficult to maintain good device performance, and improving the performance deficiency of CGSe thin film solar cell devices has been one of the research projects that many researchers strive to break through. A major problem in CGSe devices is the recombination of carriers at the space charge region interface. As the gallium content increases, the cation inversion (In Cu/GaCu) and anion vacancy (V Se) defects tend to form defect states at very deep band gap sites, forming recombination centers, resulting In reduced device performance. Meanwhile, at higher gallium content, the fermi level of CGSe absorber/buffer interface is located closer to the middle of the bandgap, so as the bandgap of CGSe increases, recombination near or at the interface becomes more pronounced. In addition, the device has the problems of higher contact resistance between the back contact metal electrode such as Mo and CGSe absorption layer, higher contact resistance between the gate electrode such as Au and Ni and window layer, and the like. Although CGSe thin film solar cell devices still have many problems to be solved, the wide bandgap semiconductor characteristics are quite matched to the wavelength of the underwater spectrum, so CGSe thin film solar cells still have great potential as underwater solar cells. Therefore, developing a novel flexible thin film solar cell with a wide band gap CGSe becomes one of the problems to be solved in the art. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a wide-band gap CGSe flexible thin-film solar cell and a preparation method th