Characterization of Ionic-electronic Transport and Recombination in Perovskite Solar Cells under Multi-biasing Conditions

Abstract

Perovskite solar cells (PSCs) are among the most promising photovoltaic technologies, offering high efficiencies and low fabrication costs. However, their commercialization remains limited by stability issues and incomplete understanding of the intrinsic mechanisms governing device performance. Particularly, slow mobile-ion dynamics can modulate charge recombination and extraction, strongly affecting device operation. Here, we use impedance spectroscopy (IS) to investigate the underlying processes that govern the current-voltage (J-V) response of PSCs under operational conditions. To this end, we combine J-V, SunsVoc and IS measurements using a multi-bias approach to analyze p-i-n PSCs under short-circuit (SC) and open-circuit (OC) conditions. Complementary, drift-diffusion (DD) simulations and equivalent circuit model (ECM) analysis on IS under SC conditions enable extraction of key transport properties, including carrier mobilities, mobile ion concentration, and shunt resistance. Across the simulated parameter space, low-frequency dark resistance is determined by shunt resistance, and nearly independent of recombination rates or mobile ion concentration. Therefore, the associated dark low-frequency RC time constant cannot be directly interpreted as a recombination lifetime. Under OC conditions, we further evaluate the coupled effects of ionic motion and energy band offsets on recombination mechanisms, comparing the ideality factor derived across techniques. This integrated experimental-theoretical framework provides deeper insight into the electronic and ionic processes governing PSC performance.