Low-frequency noise and impedance spectroscopy of device structures based on perovskite-graphene oxide composite films

We present the results of studies of low-frequency noise and impedance spectroscopy (IS) in operating planar structures based on films of organic-inorganic halide perovskite CH 3 NH 3 PbBr 3 with and without embedded graphene oxide (GO) flakes as active layers of field-effect transistors and memory chips. It is shown that 1/ f flicker noise dominates at low frequencies, while white shot-noise resulting from dark current fluctuations is the limiting noise at high frequencies. It is demonstrated that at similar currents the current noise power spectral density, S I , values are lower by factor ~ 4 for the film CH 3 NH 3 PbBr 3 :GO with respect to that for the film CH 3 NH 3 PbBr 3 without GO flakes, thus it is concluded that GO flakes act as a trap passivation. The IS results show that under identical conditions the Cole-Cole plots for both films are in good agreement with the equivalent circuit model and represents series resistance, recombination resistance and geometric capacitance, respectively, which arise due to charge accumulation, charge transfer resistance and/or additional interfacial electronic states. The decrease in the noise density by factor 4 in the perovskite films with GO flakes is attributed to the higher conductivity of these films as well as to more uniform distribution of carriers over the sample cross section. The obtained results provide the way to improve the performance of next generation of organic-inorganic perovskite optoelectronic devices.