Enhanced Sb2Se3 solar cell performance through theory‐guided defect control

Defects present in the absorber layer largely dictate photovoltaic device performance. Recently, a binary photovoltaic material, Sb₂Se₃, has drawn much attention due to its low‐cost and nontoxic constituents and rapid performance promotion. So far, however, the intrinsic defects of Sb₂Se₃ remain elusive. Here, through a combined theoretical and experimental investigation, we revealed that shallow acceptors, Se_Sb antisites, are the dominant defects in Sb₂Se₃ produced in an Se‐rich environment, where deep donors, Sb_Se and V_Se, dominate in Sb₂Se₃ produced in an Se‐poor environment. We further constructed a superstrate CdS/Sb₂Se₃ thin‐film solar cell achieving 5.76% efficiency through in situ Se compensation during Sb₂Se₃ evaporation and through careful optimization of absorber layer thickness. The understanding of intrinsic defects in Sb₂Se₃ film and the demonstrated success of in situ Se compensation strategy pave the way for further efficiency improvement of this very promising photovoltaic technology. Copyright © 2017 John Wiley & Sons, Ltd.