Effect of Pb-site doping on the structure, electronic and mechanical properties of CsPbI3 perovskite: A first-principles study

Abstract

CsPbI3 has received a great deal of attention as the light-harvesting component of pure inorganic perovskite solar cells (PSCs). It is revealed that Pb-site doping is an effective way to enhance the electrical and optical properties of CsPbI3 compared with other methods. In this study, within the framework of the density functional theory (DFT), first-principles method was used to investigate different Pb-site ionic doping effect on the structural, mechanical, electrical, and optical properties of CsPbI3. We considered totally 11 doping elements, each with a doping concentration of 12.5 % (denoted as CsPb0.875M0.125I3, M is the doping element). The results revealed that all the doping systems are structurally stable with decreased bandgap values compared with the pristine CsPbI3. CsPb0.875M0.125I3 (M=Ge, Sn) exhibits similar behavior to CsPbI3, while CsPb0.875M0.125I3 (M= As, Sb, Bi) series present electron-doping character and CsPb0.875M0.125I3 (M=Ga, In, Tl) shows hole-doping effect. Mechanically, all the other elements mono-doped CsPbI3 satisfy the stability requirement except CsPb0.875Ga0.125I3. Moreover, most of doping systems show enhanced the absorption strength in the visible light region. By synthetically considering the mechanical, electronic and optical properties, it is suggested that CsPb0.875M0.125I3 (M=Sb, Fe) exhibit relatively superior characteristics compared with pristine and other elements mono-doped CsPbI3. Results obtained in the present work may provide valuable guidance for the synthesis and the performance refinement of all-inorganic CsPbI3-based PSCs in the future.