Research On Thin Film A-Si Solar Cells Based On Flexible Substrate

As a renewable energy, photovoltaic industry has grown rapidly worldwide. It is important to research the a-Si thin film solar cells for the costs of materials increase rapidly. This research is about the fabrication of thin film a-Si solar cells based on the flexible substrate (polymer).This kind of solar cells have many advantages such as: flexible, high quality/power ratio, light weight.The PI (polymide) film is choosed as the flexible substrate for its good heat resistance, good mechanical strength and so on. An inverse solar cells structure"PI film/Al electrode/N/I/P/TCO electrode"is designed for the PI film has a low transparence. And the process steps to fabricate this kind of flexible solar cells are researched in details.As the gas released from the PI film deteriorate the a-Si films which are deposited by PECVD at a high temperature about 200～300℃. This research adds a"prebake"process to solve this problem. And then, an optimized aluminium fabrication process is achieved, which offers a Al electrode with high conductivity and stick to PI film tightly.The wide bandgap P type a-SiC:H layer is researched to fabricate a good"window layer"for the solar cells. The influence of RF power and substrate temperature about the quality of the intrinsic a-Si:H layer is researched. And the dark conductivity (δd) of the N type a-Si:H layer is researched for it is direct deposited on the Al back electrode.Fabricate a ITO (In₂O₃:Sn) layer as the front electrode with the average visible tramittance over 80%, electrical resistivity 4.0×10^-4Ω.cm through electron-beam vaccum evaporation technology.Finally, we get a single junction flexible a-Si solar cells with V_oc=0.12V, J_sc=0.75mA/cm², and Voc=0.07V, J_sc=0.46mA/cm² (bending).