Heterojunction interface engineering of C 60 electron transport layer insertion enables efficient Cd-free Sb2Se3 solar cells

Antimony selenide (Sb2Se3) 2 Se 3 ) emerges as a promising semiconductor for solar energy conversion, attributed to its high light absorption and excellent photoelectric properties, coupled with notable stability and consistent stoichiometry. Yet, its application in thin-film solar cells is limited by non-radiative recombination losses at suboptimal heterojunction interfaces. Addressing this, we propose a strategy employing a C 60 electron transport layer (ETL), thermally evaporated between the Sb2Se3 2 Se 3 absorber and SnOx x buffer layer. This approach not only increases the carrier density in SnOx x but also passivates harmful defects like VO O and OH-,- , thus reducing interfacial recombination. Incorporating C 60 ETL improves the fill factor (FF) and open-circuit voltage (VOC) V OC ) of the Sb2Se3 2 Se 3 device, achieving a maximum power conversion efficiency (PCE) of 6.65 %. This finding highlights the significance of ETL-dependent interfacial engineering in enhancing Sb2Se3 2 Se 3 solar cell performance, offering a novel and accessible solution to the primary challenge in developing Cd-free Sb2Se3 2 Se 3 solar cells.