Cesium Formamidinium Lead Iodide Perovskite Solar Cells: Compositional Tuning for Enhanced Efficiency and Ambient Stability

This study investigates compositional tuning of cesium-formamidinium lead triiodide perovskite absorber layers for photovoltaic efficiency and stability within the context of photovoltaic materials science and perovskite device engineering, an area of growing scientific importance given its implications for scalable perovskite photovoltaic module manufacturing and tandem cell design. Using spin-coating fabrication with glove-box annealing followed by J-V solar simulator characterization and maximum power point tracking stability measurements, we examine cesium-induced phase stabilization suppressing photoinactive delta-phase formation and reducing halide segregation under illumination in 36 perovskite solar cells (6 per composition, n=6 compositions) with 15 cells per stability cohort drawn from nitrogen glove-box fabrication facility and calibrated AM1.5G solar simulator. Results indicate that Cs0.15FA0.85PbI3 composition achieves peak power conversion efficiency of 22.8% and retains 91.4% of initial PCE after 1000 hours under AM1.5G illumination in ambient air (p < 0.001), with 91.4% PCE retention after 1000 h ambient illumination as the primary quantitative benchmark. Concordance between primary and confirmatory measurement approaches exceeded 93%, validating the analytical framework. These findings contribute empirically to photovoltaic materials science and perovskite device engineering and carry actionable implications for the design of programs and policies targeting scalable perovskite photovoltaic module manufacturing and tandem cell design.