Inductive and capacitive hysteresis of current-voltage curves: unified structural dynamics in solar energy devices, memristors, ionic transistors, and bioelectronics

Hysteresis observed in the current-voltage curves of both electronic and ionic devices is a phenomenon where the curve's shape is altered on the basis of the measurement speed. This effect is driven by internal processes that introduce a time delay in the response to an external stimulus, leading to measurements being dependent on the history of the past disturbances. This hysteresis effect has posed challenges, particularly in solution-processed photovoltaic devices such as halide perovskite solar cells, where it significantly complicates the evaluation of performance quality. In other devices, such as memristors and organic electrochemical transistors for neuromorphic applications, hysteresis is an inherent aspect of their functionality, facilitating transitions between different conductivity states. Natural and artificial ionically conducting channels also exhibit pronounced hysteresis, a crucial component for generating action potentials in neurons. In this study, we aim to categorize various forms of hysteresis by identifying shared elements among diverse physical, chemical, and biological conducting systems. Our method involves examining hysteresis from multiple angles, using simplified models that capture essential response types. We analyze system behavior using techniques such as linear sweep voltammetry and impedance spectroscopy and transient currents resulting from small voltage steps. Our investigation reveals two primary hysteresis types based on how current responds to rapid sweep rates: capacitive hysteresis and inductive hysteresis. These terms correspond to the dominant component in the equivalent circuit, determining the transient time response. Remarkably, these concepts provide insights into vastly different systems, spanning solar cells, capacitors, transistors, electrofluidic nanopores, and protein ion channels. The consistency in electrical responses across the different cases enables the identification of the primary cause of hysteresis. We also elucidate the frequency dependence of hysteresis and the stepwise responses of solar cells, illustrating how fundamental relaxations contribute to the overall surplus or deficit of current during extensive voltage sweeps that define the current-voltage curve.