Effect of Mesoporous TiO2 on Charge Dynamics of RbCsMAFA-Based Quadruple Cation Perovskite Solar Cells

The electron transport layer of mesoporous TiO2 (mp-TiO2) plays a pivotal role in the performance and development of perovskite solar cells (PSCs). In order to understand the charge kinetics occurring in the bulk and at the selective interfaces, we studied quadruple cation RbCsMAFA-based PSCs deposited by spin-coating, with and without mp-TiO2. The mp-TiO2-free PSCs demonstrated a power conversion efficiency (PCE) of 12.10% with low short circuit current (Jsc) whereas a higher PCE of 16.12% with increment in Jsc was measured for the PSCs with mp-TiO2. The interfacial charge kinetics of PSCs was investigated by bias-dependent electrochemical impedance spectroscopy (EIS). The PSCs fabricated with mp-TiO2 showed a lower recombination and higher charge carrier lifetime. Further, by performing Mott-Schottky measurements, the built-in potential and doping density of immobile ions were evaluated.