9.7%-efficient Sb2(S,Se)3 solar cells with a dithieno[3,2-b: 2′,3′-d]pyrrole-cored hole transporting material

Abstract

Antimony selenosulfide, Sb₂(S,Se)₃, is a promising next-generation solar cell material with superior photovoltaic properties and high stability. However, the efficiency of Sb₂(S,Se)₃ solar cells lags far behind its theoretical value and other well-established thin-film solar cells. Herein, we report a one-step hydrothermal process by employing selenourea as a selenium source for a single-phase and compact Sb₂(S,Se)₃ light absorber film, which possessed a desirable bandgap of 1.50 eV. When a low-cost and planar dithieno[3,2-b:2′,3′-d]pyrrole-cored small molecule (DTPThMe-ThTPA) is used as the hole transporting material, the interfacial energy level alignment is optimized. We disclose that chemical interaction formed between neighbouring thiophene and Sb atoms is critical for carrier collection and suppression of charge recombination, resulting in a champion efficiency of 9.7% with DTPThMe-ThTPA and increased stability, which is comparable to the device based on conventional Spiro-OMeTAD.