Contribution to improve the performances of Cu2ZnSnS4 thin-film solar cell via a back surface field layer

Abstract

In this research work, SCAPS-1D simulator is used to model and investigate the CZTS (Cu2ZnSnS4) solar cells. A substrate cell structure ZnO/CdS/CZTS/Mo was used as a base model. A novel structure is proposed in which a back surface field (BSF) layer is inserted in order to improve the solar cell performances. A CZTS layer has been added as BSF layer. The obtained results present an increase in efficiency of CZTS solar cell from 12.03% to 14.03%. An optimization of different physical parameters (Thickness and doping concentration) of BSF layer has been done, the improvement on the electrical parameters of the solar cell was achieved (ƞ = 14.16%, Voc = 0.997 Volt, Jsc = 24.63mA/cm2 and FF = 57.65%) according to 1E18 cm−3 value of doping concentration and 0.1 μm thickness, the enhancing in the electrical efficiency is about 17.70%. The optimum value of BSF layer thickness is considered as 70 nm according to 1E18cm−3 of doping concentration with a conversion efficiency of 14.11% under 1.5 AMG illuminations, which corresponding to following electrical parameters: Jsc = 24.57 mA/cm2, Voc = 0.988 Volt, and fill factor = 58.06%. Also, at the end, the effect of the BSF layer on the band diagram and the generation-recombination profiles of CZTS solar cell is discussed.