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Hydrogeneted amorphous silicon (a-Si:H) based solar cells are promising candidates for future developments in the photovoltaic industry. In fact, amorphous silicon technology offers significant advantages including low cost fabrication and possibility to deposition on flexible substrat as well as low temperature fabrication. Much progress has been made since the first single junction cell in amorphous silicon made in 1976 by Carlson and Wronski. However, the performance of the solar cells based on a-Si:H is limited by the high defect density and degradation induced by exposure to light, or Staebler-Wronski effect. To become competitive, the performance of the solar cells based on a-Si:H must be improved. In order to improve the performance of a-Si:H solar cells, much research is directed to optimization techniques. The improvement in performance is therefore based on the optimization of the different layers of the solar cell, in particular, the window layer and the absorber layer (intrinsic). The aim of this work is to give an overview on the different techniques and strategies that is used to improve the performance of solar cell. This work is therefore focus in three main areas: first, optimization of window layer, in particular, the p/i interface using wide band gap alloys such as a-SiC:H, second development of high quality absorber layer using band gap engineering, and alloys such as a-SiGe:H. last, optimizing n-type layer and i/n interface. |
