Simulation-Based Performance Optimization and Mechanistic Analysis of CsPbIBr₂/CsPbBr₃ Stacked All-Inorganic Perovskite Solar Cells in Low-Temperature Working Environments

Abstract

While CsPbBr 3 has emerged as a representative of high-stability perovskite materials, it still faces certain bottlenecks in its development, including a relatively narrow spectral response range and challenges in aligning its energy band structure. This work involves the construction of a CsPbIBr 2 /CsPbBr 3 P−N stacked heterostructure, using two closely related perovskite materials, CsPbBr 3 and CsPbIBr 2 , which share analogous energy band structures while displaying contrasting electrical characteristics. SCAPS-1D software was utilized for numerical evaluations to examine the impact on device performance when the instrument was operated at low temperatures. The results indicate that between 250 and 300 K, device performance remains remarkably stable with negligible fluctuations. Comparative analysis shows that the CsPbIBr 2 /CsPbBr 3 heterostructure outperforms single-layer configurations, effectively merging the distinct benefits of both materials. By leveraging the distinct roles of CsPbIBr 2 and CsPbBr 3 within the heterostructure, we determined the optimal thickness for each layer of the materials. This work analyzed the impact of increased doping concentration on performance metrics, including energy band structure, carrier recombination rate, and external quantum efficiency. By integrating processing methods with material optical properties, the optimal doping concentration for improved carrier migration was determined. Additionally, defect density levels were optimized in the work, resulting in enhanced performance of perovskite-layered devices. Consequently, we successfully accomplished the objective of optimizing PSCs for low-temperature operation, yielding an impressive PCE of 22.01% and an FF of 91.17%, indicative of remarkable efficiency and robustness. The CsPbIBr 2 /CsPbBr 3 heterostructure assembled in this work provides a viable path to achieving both remarkable efficiency and stability in low-temperature-operating all-inorganic perovskite solar cells.