Lead halide perovskites are mixed electron-ion conductors that support high rates of solid-state ion transport at room temperature, in addition to conventional electron and hole conduction. Mass transport mediated by charged defects is responsible for unusual phenomena such as current-voltage hysteresis in photovoltaic devices, anomalous above-bandgap photovoltages, light-induced lattice expansion and phase separation, self-healing, and rapid chemical conversion between halides. We outline the principles that govern ion transport in perovskite solar cells including intrinsic (point and extended defects) and extrinsic (light, heat, electrical fields, and chemical gradients) factors. These microscopic processes underpin a wide range of reported observations, including photoionic conductivity, and offer valuable directions for both limiting ion transport, where required, and harnessing it to enable new functionality.
Bibliographical noteFunding Information:
This work was supported by the EPSRC (Grant No. EP/ K016288/1), the Leverhulme Trust, and the Royal Society University Research Fellowship scheme. This project has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (Grant No. 756962).
All Science Journal Classification (ASJC) codes
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry