Efficiency Limits of SnS Thin Film Solar Cells

Tin sulfide (SnS) is a non-toxic and earth abundant material belonging to group IV–VI, and due to its optimum band gap has been considered as a suitable material for absorber layer in photovoltaic solar cell applications. However, despite its optimum band gap for photovoltaic conversion the maximum power conversion efficiency achieved up to now in experimental devices for SnS-based solar cell is only 4.6%, which is far below its related Shockley-Queisser limit. In this paper, the main photovoltaic parameters of a SnS/CdS/ZnO solar cell are analysed with the aid of MATLAB and Solar Cell Capacitance Simulator software (SCAPS). The expected efficiency for a SnS/CdS/ZnO solar cell structure composed by layers without defects is about 28%. However, the performance of SnS-based solar cell is highly dependent upon material properties like band tailing, temperature, thickness of the absorber material and defects in the absorber layer and in the interface buffer/absorber. The effect of the defects on the overall performance of SnS-based solar cells is calculated and discussed and the results are compared with reported experimental SnS/CdS solar cells.