Analysis of the ionic and dielectric properties of perovskites by impedance spectroscopy

For understanding the operation of perovskite solar cells and light-emitting diodes, knowledge dielectric properties is indispensable. The perovskites are frequency dependent due to presence moving ions, which complicates interpretation impedance spectra. Using Au/CsPbI2Br/Au capacitors with varied layer thickness as a model system, we demonstrate that in dark, an extended Maxwell circuit consistently describes data. From dependence resistivities, both electronic ionic conductivities obtained, whereas combination capacitances characteristic frequencies for space-charge formation determines ion diffusion coefficient density. At low frequencies, slow transient process fixed time constant ∼0.1 s occurs, governed by conductivity, being independent illumination strength sample thickness. As possible mechanism, propose spatial reorganization ions within accumulation at electrode/perovskite interface.