Study And Preparation Of Thin Film Solar Cells On Flexible Substrates

Photovoltaic is a very perspective field among various renewable energies. Solar cells can only establish their stable position on the market only if they are also economically profitable. R&D is not only focusing on enhancing the conversion efficiency and the stability of the solar cells, but also trying to find processes and technologies reducing the costs. Flexible Cu(In,Ga)Se2 (CIGS) solar cells are therefore very attractive because of their high conversion efficiencies, their low cost potential and the applications in many fields. The focus of the thesis was to apply innovation for development of next generation CIGS solar cells based on flexible foils and also novel devices for better utilization of solar spectrum to yield higher efficiency and performance stability.The major challenge in development of CIGS solar cells on flexible substrates like polyimide and aluminum foils lies in finding a technology which is suitable for durable temperature of the substrate, thermo-physical properties of layers, control of large-area uniformity. At the same time, this technology also meets the demand of structure, properties and low cost.The thesis discusses the key technologies for preparing large-area solar cells based on flexible foils. In order to control large-area uniformity of solar cell, model and controlling method for gas distribution in Roll-to-Roll process were brought forward and the method was confirmed by experiment successfully. A new method for preparing texture surface was suggested, some of factors for affecting the texture was discussed, and the process parameters was determined. In order to get high quality composite films at low temperature and high productivity, ion beam assisted reactive sputtering was put forward, the physical mechanism and reaction model was discussed, and the technology was verified by sputtering Al2O3 blocking film, and the technology can be used in preparing CIGS at low temperature.Finally, a method named Roll-to-Roll technology was adopted in preparing CIS solar cell on the Al foil substrate. The whole progress was performed in vacuum atmosphere, CdS was replace with ZnO film which was prepared in low-energy sputtering technology. A simplified ion-beam-assisted sputtering technology was used in the deposition of CIS. The photovoltaic properties of the CIS film are significant. In addition, some a-Si films were prepared, and the influence of preparing technics on structure, composition, photovoltaic property of a-Si was studied.