An effective engineering with simultaneous carrier density enhancement and interface optimization enables efficient Sb2Se3 solar cells

Abstract

Insufficient free carrier concentration (1013 cm−3) has been considered one of the main culprits limiting the photovoltaic performance of antimony triselenide (Sb2Se3) thin-film solar cells. In this work, a thin platinum (Pt) intermediate layer is introduced into the system to address this issue for untreated Sb2Se3 absorber films. PtSe2 formation has been found within the absorber which directly contributes to the increased carrier density. The built-in voltage and back contact of the device are found to be optimized thanks to the increased carrier density. Meanwhile, both the interfacial and bulk recombination of the device are simultaneously reduced by passivating detrimental defect states at the Sb2Se3/CdS interface and the bulk film after Pt intermediate layer introduction. As a result, the overall photovoltaic performance of the substrate structured Sb2Se3 thin-film solar cell has been effectively improved, leading to a competitive power conversion efficiency of 7.49 % for the champion device. This work demonstrates an effective strategy for overcoming the key challenge of further efficiency improvement of Sb2Se3 solar cells.