Direct Evaluation of Perovskite Solar Cell Performance and Stability Using Transient and Steady‐State Transport Measurements

Abstract In this study, a direct correlation between charge transport properties and the stability of perovskite solar cells (PSCs) using time‐ and frequency‐domain measurements is provided. Faster charge carrier extraction and reduced nonradiative recombination serve as key indicators of stability and performance, implying the prevention of charge accumulation and defect formation, thereby reducing degradation. Stable, phase‐pure formamidinium lead iodide (FAPbI₃, or FAPI) templated with 2D perovskite‐based PSCs is compared, against conventional methylammonium chloride (MACl)‐stabilized FAPI‐based PSCs. Lattice‐engineered, strain‐relaxed growth in 2D‐templated FAPI‐based devices leads to enhanced charge extraction and faster transport timescales, as confirmed by Transient Photocurrent (TPC) and Intensity‐Modulated Photocurrent Spectroscopy (IMPS) measurements are demonstrated. Furthermore, Transient Photovoltage (TPV) and Impedance Spectroscopy (IS) reveal reduced non‐radiative recombination losses in these 2D‐templated FAPI devices. Moreover, the use of these techniques highlights their effectiveness in monitoring fundamental processes and deriving key parameters to evaluate the intrinsic stability of PSCs, also under prolonged UV light exposure. This integrated approach underscores the critical role of combining time and frequency‐domain analyses in understanding the performance, durability, and long‐term stability of PSCs.