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Fabrication of Superstrate Copper Indium Sulfide Solar Cell Avoiding Titanium Dioxide Blocking Layer
Safi Samghabadi, Farnaz | 2015
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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 47345 (04)
- University: Sharif University of Technology
- Department: Physics
- Advisor(s): Taghavinia, Nima
- Abstract:
- During recent years, thin-film solar cells based on chalcogenide light absorbers with CuInxGa1-xS(Se)2 compound have attracted considerable attraction due to their desirable band gaps and demonstrated high power conversion efficiencies. These solar cells are fabricated under two categories named as ‘substrate’ and ‘superstrate’, generally. The best reported energy conversion efficiency belongs to substrate type (sodalime glass/Mo/absorber layer/buffer layer/window layer) CIGS solar cells, most have been fabricated with vacuum processes. In spite of this, superstrate solar cells (transparent conducting oxide/blocking layer/buffer layer/absorber layer/back contact) provide easier and cheaper fabrication processes. In these solar cells, electron blocking layer prevents from transportation of photogenerated electrons in buffer/absorber interface and recombination of them with holes from back contact. Avoiding this layer and substituting that with TCO layer, one can make a structure like TCO/absorber layer/buffer layer/window layer (TCO/CIS/CdS/ZnO) which can work as a bifacial solar cell too.The notable point in such a structure is the deposition of absorber layer with p conductance on TCO layer and approaching the substrate structure. In this research, we made use of solution-based processes for deposition of all layers. CuInS2 absorber layer was deposited from molecular-based precursor solution and through spin coating process and the deposition of cadmium sulfide buffer layer was done with chemical bath deposition method. Investigating various parameters in absorber layer like stoichiometric ratio and different precursors, eventually indium acetate containing ink was selected for optimizing other layers performance. Analysis revealed that deposition of a very thin layer of indium sulfide semiconductor utilizing spray pyrolysis method before absorber deposition on TCO causes photovoltaic performance by making change in band energies. Finally, aiming fabrication of superstrate structure through omitting TiO2 blocking layer, with two steps deposition of cadmium sulfide in temperature 80ᵒC and zinc oxide window layer, 0.5% efficiency and 4.18 mA/cm2 current denisty and by substituting window layer with organic PCBM layer 0.75% efficiency and 4.85mA/cm2 current density was achieved
- Keywords:
- Copper Indium Sulfide Solar Cell ; Electron Blocking Layer ; Solution-Based Processes
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