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.