Efficient Sb2Se3/CdS planar heterojunction solar cells in substrate configuration with (hk0) oriented Sb2Se3 thin films

Antimony selenide (Sb 2 Se 3 ) based solar cell technology has experienced rapid development with demonstrated cell efficiency reaching ̴ 9.2% for devices in substrate configuration, hence motivating more intense research investigations. Though the effect of crystallographic orientation in this non-cubic material on device performance is now well understood, the influence of composition and intrinsic defects remains debatable. In this work we describe the fabrication and device characteristics of Sb 2 Se 3 solar cells designed in the substrate configuration (SLG/Mo/Sb 2 Se 3 /CdS/i-ZnO/ITO). Notably, Sb 2 Se 3 absorber layers with a predominant (hk0) orientation were deposited in a single step by e-beam evaporation of pre synthesized bulk source material. As grown precursor Sb 2 Se 3 thin films were subjected to reactive thermal annealing treatment in the presence of Se source at different temperatures for enhancing their crystalline quality and balancing their stoichiometry. Analysis of the completed solar cells indicated improved efficiencies post reactive thermal annealing process, with the best performing devices exhibiting a power conversion efficiency (η) of ~4.34% for an absorber annealed at a temperature of 350 °C. The improved efficiency is ascribed to the observed changes in chemical composition of the absorber layer and the possible formation of related beneficial antisite defects. • (120) oriented polycrystalline Sb 2 Se 3 thin films were deposited by e-beam evaporation of pre synthesized bulk in single step. • Stoichiometry and concentration of native defects was modified through reactive thermal annealing (RTA) of as grown absorber layers under Se atmosphere. • Sb 2 Se 3 heterojunction solar cells were completed in the substrate configuration of Mo/Sb 2 Se 3 /CdS/i-ZnO/ITO. • Best performing solar cells exhibited power conversion efficiency ~4.34% for the absorber layers annealed at temperature of 350 °C. • Improvement in the efficiency was attributed to the passivation of native defects resulting from the ReTA of as grown Sb 2 Se 3 thin films.