Ionic-to-electronic current amplification in hybrid perovskite solar cells: ionically gated transistor-interface circuit model explains hysteresis and impedance of mixed conducting devices

TL;DR

This paper introduces a transistor-based model for hybrid perovskite interfaces that explains hysteresis and impedance, revealing ionic-to-electronic current amplification and enabling design of tunable electronic components.

Contribution

It presents a novel interface circuit model that captures ionic-electronic interactions and explains device hysteresis and impedance in hybrid perovskite devices.

Findings

Amplification of electronic current by ionic charge redistribution.

Verification of the model with drift-diffusion simulations.

Potential for designing tunable capacitor- and inductor-like components.

Abstract

Mobile ions in hybrid perovskite semiconductors introduce a new degree of freedom to electronic devices suggesting applications beyond photovoltaics. An intuitive device model describing the interplay between ionic and electronic charge transfer is needed to unlock the full potential of the technology. We describe the perovskite-contact interfaces as transistors which couple ionic charge redistribution to energetic barriers controlling electronic injection and recombination. This reveals an amplification factor between the out of phase electronic current and the ionic current. Our findings suggest a strategy to design thin film electronic components with large, tuneable, capacitor-like and inductor-like characteristics. The resulting simple equivalent circuit model, which we verified with time-dependent drift-diffusion simulations of measured impedance spectra, allows a general description and interpretation of perovskite solar cell behaviour.