Negative Transient Spikes in Halide Perovskites

The internal crossfire of ionic and electronic effects in perovskite devices forms a complex analysis problem that has not been fully solved yet. Specifically, halide photovoltaic perovskites show a photoinduced ionic inductance behavior in current transient measurements, evidenced by ubiquitous negative spikes. Here, we provide a consolidated interpretation of these observed chemical mechanisms by independent measurement routes (frequency and time domain) in order to solve an elusive topic in the development of perovskite solar cells for more than a decade. From this operational pathway, we specifically study the light-dependent negative overshoot photocurrent phenomena in the time-domain discharge of the chemical inductor, which is a transversal mechanism found in a multitude of chemical, biological, and material systems. Our results establish a general framework to understand the inductive transient effects observable in new and important applications of halide perovskites, capable of emulating the electrical activity of neurons and synapses when acting as memristors.