Simulation and Optimization of Back Surface Field for Efficient HIT Solar Cells

Abstract

We investigate an appropriate material for the optimisation of Back Surface Field (BSF) layer in Heterojunction with Intrinsic thin layer (HIT) solar cells: ITO/p-a-Si:H/i-a-Si:H/n-c-Si/BSF/Ag. The obtained results show that it is important to choose hydrogenated amorphous silicon to create the BSF layer instead of crystalline silicon as in the case for conventional HIT solar cells. The use of hydrogenated amorphous silicon creates a significant band discontinuity at the valence band due to the presence of the heterojunction at the interface n-c-Si/n++-a-Si:H. We also show that increasing the BSF layer thickness degrades the solar cell J-V characteristic due to the low diffusion length and lifetime of the minority carriers and also because of the increase of the recombination rate in this heavily doped layer. The global device optimization was performed with SCAPS–1D software under STC conditions and the results show that a considerable efficiency of 27.44\u2009% can be achieved.