Crystalline Si thin film n-type solar cells : a screen printed rear junction approach

In this work we present large area crystalline silicon thin film n-type solar cells. The rear junction is formed by growth of an n-type Chemical Vapour Deposition (CVD) layer on highly p+-doped substrate.The arising rear side emitter geometry of the solar cell features an n+ phosphorous diffused front-surface-field on n-type thin absorber deposited by high temperature CVD. Apart from the deposition of the thin film all processing steps rely on already industrially implemented processing steps such as open tube furnace POCl3 diffusion, PECVD SiNx deposition and thick film screen printing technique. Following simulations, different base doping levels of the CVD layers were tested. The best 96 cm2 large solar cell with a 30 μm thick epitaxial wafer equivalent showed an efficiency of 13.5% for a p+ Cz-Si substrate and 12.3% for the best mc-Si device, respectively