Compatibility analysis of novel inorganic cesium perovskites with emerging charge transport layers through design optimization

The widely used Methylammonium lead iodide perovskite face stability challenges due to the organic methylammonium component, which degrades under environmental factors like moisture and heat, leading to toxic lead leakage, poisoning the surroundings. This study analyzes the compatibility of alternative inorganic, nontoxic, cesium-based planar (n-i-p) perovskite solar cells (PSCs), specifically Cs₃Bi₂I₉ and CsSnI₃, with various charge transport layers (CTLs) to enhance power conversion efficiency (PCE). A total of eight PSC configurations were simulated using SCAPS-1D software, with the selected CTLs including GO, MoS₂, CeO₂ and WO₃. The initial optimization step involved adjusting the absorber thickness, leading to enhanced photon absorption and increased PCE across all configurations. Further optimization of CTL doping, carrier mobility, and electron affinity improved band alignment, electric potential distribution, and cell conductivity. These optimizations reduced recombination losses and enhanced charge carrier extraction. A second round of absorber thickness optimization was then performed, accounting for the changes induced by the previous steps. As a result, the PCE improved significantly, with the highest efficiency reaching 21.52% in the GO/CsSnI₃/CeO₂ structure. Other optimized configurations, such as GO/CsSnI₃/WO₃ and MoS₂/CsSnI₃/WO₃, achieved PCE values of 21.4% and 15.64%, respectively. This multi-step optimization demonstrates that cesium-based perovskites, when combined with properly tuned CTLs, can achieve high efficiencies, positioning them as promising materials for the next generation of photovoltaics.