Identification of Asymmetric Interfacial Recombination in Perovskite Solar Cells through Impedance Spectroscopy

Nonradiative carrier recombination plays a major role in affecting solar cells' performance and power conversion efficiency (PCE). Herein, we utilize illumination-side-dependent impedance spectroscopy (ISD-IS) to study the different carriers' recombination in complete perovskite solar cells (PSCs) with three different commonly used electron transport materials (ETMs). We have conducted the ISD-IS measurements of PSCs subjected to different illumination intensities and under different operation conditions (i.e., open circuit and short circuit). The results point to unbalanced interfacial recombination in the tested devices, whereby higher recombination occurs near one of the interfaces of the perovskite layer. By changing the illumination intensity and/or operation point, the dominant site of recombination (i.e., interface or bulk) inside the PSC changes depending on the carrier transport materials of the PSC structure. Overall, the ISD-IS measurements of the PSCs reveal the effects of different ETMs on the losses and recombination in PSCs.