Low-frequency carrier kinetics in triple cation perovskite solar cells probed by impedance and modulus spectroscopy

Organometallic halide perovskites-based solar cells have emerged as next-generation photovoltaic technology. However, many of its intriguing optoelectronic properties at low frequency are highly debated. Here, we investigate the low-frequency carrier kinetics of the state-of-the-art triple cation perovskite Cs(0.06)FA (0.79)MA(0.15)Pb(I0.85Br0.15)(3) solar cells using bias-dependent impedance and modulus spectroscopy under dark and illumination conditions. We observe a strong dependence of dielectric permittivity on frequency in 1 Hz to 1 MHz region with a dielectric relaxation, which is observed to follow the MaxwellWagner type interfacial polarization possibly originating from the grain boundary/ionic defects. Furthermore, correlating the impedance and modulus spectra reveals the localized charge carrier relaxation in this triple cation device from which we obtain a phenomenological picture of the hopping process and developing an understanding of the charge carrier kinetics in these high-efficiency perovskite photovoltaics. (C) 2021 Published by Elsevier Ltd.

Automated summary

In this study, the low-frequency carrier kinetics of organometallic halide perovskite-based solar cells were investigated. It was found that the dielectric permittivity showed a strong frequency dependence with dielectric relaxation, indicating localized charge carrier relaxation and hopping processes in these high-efficiency perovskite photovoltaics.