Effective additive for enhancing the performance of Sb2S3 planar thin film solar cells

Sb2S3 is a promising photovoltaic absorber with appropriate bandgap, excellent light absorption coefficient and great stability. However, the power conversion efficiency (PCE) of Sb2S3 planar thin film solar cells is unsatisfactory for further commercial application due to low crystallinity and high resistivity of Sb2S3 film. Here, we introduce an additive of 4-Chloro-3-nitrobenzenesulfonyl Chloride (CSCl) to alleviate these problems. The CSCl molecular contains two terminal Cl with lone pair electrons, which have the interaction with Sb atoms. Thus, the Sb2S3 film with enhanced crystallization and low trap states has been obtained and the resistivity is also decreased. Furthermore, CSCl additive raises the Fermi level of the Sb2S3 film, thereby enhancing the transport of electron from Sb2S3 to TiO2. Consequently, the optimal PCE of Sb2S3 solar cells is raised from 4.20% (control device) to 5.84%. Our research demonstrates a novel additive to enhance the photoelectric performance of Sb2S3 solar cells.