Thermally activated defect-assisted recombination and stability degradation in MASnI3 perovskite solar cells: A correlated J-V and impedance study

The performance and thermal stability of CH 3 NH 3 SnI 3 (MASnI 3 ) perovskite solar cells (PSCs) over temperature range of 270–350 K are systematically studied by current density-voltage (J-V) characteristics, electrochemical impedance spectroscopy (EIS), and defect-state evaluation. The open-circuit voltage ( V oc ) decreases from 1.063 V to 0.977 V with increasing temperature from 270 K to 350 K, and the power conversion efficiency (PCE) reduces from 28.18% to 25.72%, while the short-circuit current ( J sc ) remains nearly constant (∼33.89 mA/cm 2 ). The degradation of device performance is ascribed to the thermally activated defect-assisted recombination, as evidenced by the exponential increase in the saturation current density ( J o ). The analysis of the dark J-V characteristics indicates an activation energy of 0.68 eV, suggesting that Shockley-Read-Hall (SRH) recombination is the dominant carrier-loss mechanism. Unlike prior research that mostly focused on temperature-dependent photovoltaic parameters or using EIS for device optimization, this study establishes a direct correlation between thermally induced performance degradation and recombination dynamics by integrating J-V and EIS analyses. EIS analysis reveals a significant reduction of recombination resistance ( R rec ) and carrier lifetime ( τ ) with increasing temperature, while the series resistance ( R s ) exhibits only a minor change. This implies that device degradation is mainly governed by recombination processes rather than by charge-transport limitations. Moreover, the non-Arrhenius behavior of R rec suggests the presence of multiple thermally activated recombination pathways associated with bulk and interface defect states. These findings provide new insight into the thermal degradation mechanisms of lead-free CH 3 NH 3 SnI 3 perovskite solar cells and offer guidance to enhance their thermal stability through defect and interface engineering.