On Charge Carrier Recombination in Sb2S3 and Its Implication for the Performance of Solar Cells

Sb2S3 is widely considered to be an attractive photovoltaic material based on abundant, nontoxic elements. However, the maximum efficiency reported for solar cells based on this semiconductor does not exceed 6.5%. We have measured light intensity-dependent J-V curves, transient microwave photoconductivity, steady-state photocurrent grating, modulated photocurrent, and photoconductivity on Sb2S3-based samples. All techniques converge toward the same observation: the main recombination route controlling the density of charge carriers in the absorber is of an order greater than one and appears to stem from an exponentially decaying density of tail states within the conduction band of the material. This conclusion has direct and drastic implications for the performance of Sb2S3-based solar cells.