Evaluation of triple cation, triple anion Perovskite film quality for solar cell applications by TRMC measurements

We report on the influence of bandgap variation and surface passivation on the charge carrier dynamics of perovskite thin films, assessed via time-resolved microwave conductivity (TRMC) and steady-state photoluminescence (PL) measurements. Low-bandgap perovskite samples exhibited higher TRMC amplitudes and longer lifetimes compared to their high-bandgap counterparts, indicating lower initial recombination. Passivation further improved these properties in low-bandgap and high-bandgap films. We found a very good correlation between microwave conductivity signal amplitude and steady-state photoluminescence intensity. Both measurement techniques show clearly that the PEAI passivation on the triple-cation, triple-anion perovskite films is effective. Under low-light illumination conditions, the solar cells, realized with the low-bandgap passivated devices, demonstrated high open-circuit voltages even at low light intensities, confirming their good potential for indoor photovoltaic applications.