Poly(acrylic acid)-modified SnO2/CdS double electron transport layers for efficient and stable Sb2(S,Se)3 solar cells

Abstract

Antimony selenosulfide (Sb₂(S,Se)₃) solar cells hold significant promise for sustainable photovoltaic technology due to their adjustable band gap, high absorption coefficient and good stability. In terms of device operation, the transfer of electrons from the Sb₂(S,Se)₃ layer to the electron transport layer (ETL) plays a crucial role in improving the photovoltaic performance of solar cells. Until now, high-efficiency Sb₂(S,Se)₃ solar cells have typically employed cadmium sulfide (CdS) as the ETL. However, inadequate interface contact between the CdS and the Sb₂(S,Se)₃ layer often results in severe interface recombination, and the parasitic light absorption of CdS restricts the short-circuit current density (J_sc). Therefore, the development of high-quality CdS film along with reduction of cadmium element usage remains an import issue for the Sb₂(S,Se)₃ solar cells. Herein, the poly(acrylic acid)-modified tin oxide (PAA-SnO₂)/CdS double ETLs are introduced to improve the quality of both the CdS film and Sb₂(S,Se)₃ film, while also strengthening the interface contact between CdS and Sb₂(S,Se)₃. The power conversion efficiency of the corresponding solar cells increases from 7.45% in the control device to 8.15% in the modified device. This work provides a simple PAA-modified SnO₂-assisted CdS ETL strategy to improve the interface of CdS/Sb₂(S,Se)₃, thereby achieving efficient and stable Sb₂(S,Se)₃ solar cells.