The photoelectric and defect properties in B-sites doped α -CsPbI 3 by first-principles

Abstract The effects of (Ca 2+ , Ge 2+ , or Sn 2+ ) doping on the stability, photoelectric and defect properties of B-Sites doped α -CsPbI 3 have been investigated by first-principles calculations. The calculated results demonstrate that all doped systems exhibit negative formation enthalpies, indicating their thermodynamic stability. Furthermore, all the compounds are identified as direct p-type semiconductors with band gaps of 1.417, 1.556, 1.261 and 1.307 eV for the α -CsPbI 3 , Cs 18 Pb 17 CaI 54 , Cs 18 Pb 17 SnI 54 and Cs 18 Pb 17 GeI 54 , respectively. In the visible and near-infrared light regions, Cs 27 Pb 26 BI 81 (B = Sn, Ge) shows stronger optical absorption than α-CsPbI 3 . For the Ge-doped system, a red shift in absorption peak is observed as the doping concentration decreases. Conversely, in the Sn-doped system, a blue shift occurs in the high-energy region when the Sn concentration decreases. Except for the Cs 27 Pb 26 GeI 81 , the defect transition energy levels for the other doped systems are located near the valence band and belong to shallow defect energy levels, demonstrating their potential photovoltaic application.