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

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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 (Jsc). 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.