Design and Numerical Investigation of CsPbI<sub>3</sub>/CsSn<sub>0.5</sub>Ge<sub>0.5</sub>I<sub>3</sub> Double‐Absorption‐Layer Heterojunction Perovskite Solar Cells Based on SCAPS‐1D
Ao Zhang, Rui Duan
Abstract
CsPbI 3 material has obvious advantages in constructing stable all‐inorganic perovskite solar cells (PSCs). However, the wide bandgap (1.73 eV) of CsPbI 3 cannot effectively absorb low‐energy photons, which seriously hinders its development in single‐junction solar cells. In this study, a CsPbI 3 /CsSn 0.5 Ge 0.5 I 3 double‐absorption‐layer heterojunction PSC is constructed by SCAPS‐1D. In the results, it is shown that adding a narrow bandgap CsSn 0.5 Ge 0.5 I 3 absorption layer optimizes the band structure and energy level distribution, enhancing the device's built‐in potential and spectral absorption range. The combination of different electron‐transport layers, hole‐transport layers, and perovskite layers are stimulated, ultimately identifying the optimal material for the charge‐transport layers. In addition, the effects of internal factors (thickness and defect density of the absorption layer, interface defects, and work function of the back electrode) and ambient temperature on the overall performance of the device are investigated. The optimized power conversion efficiency of the device (fluorine‐doped tin oxide/Cd 0.5 Zn 0.5 S/CsPbI 3 /CsSn 0.5 Ge 0.5 I 3 /Cu 2 BaSnS 4 /Au) reaches 31.02%. In this study, a new attempt at the construction of stable and efficient all‐inorganic heterojunction PSC is provided.