Solid-state ionic and mixed conductors are critical across emerging electrochemical technologies. For these technologies, the ability to achieve precise spatio-temporal control over defects would yield unprecedented functionality and performance.  In IRG2, we are establishing the field of photo-ionics, in which electronically-mediated light-ion interactions control defect populations and macroscopic fluxes of defects and ions. UV/visible light represents an emerging tool for defect manipulation, where conventional control knobs such as temperature, gas atmosphere, and applied voltages fall short in terms of range, spatio-temporal precision, selectivity, or use of contacts. Direction of ion fluxes and nanoscale concentration profiles by light provides an unparalleled capability to tailor materials’ structure, properties, and performance in-situ.

The IRG integrates experiments, simulations, and data science to elucidate the mechanisms by which light-excited electronic carriers interact with dynamic ion configurations in solid-state ionic and mixed conductors. This work is filling knowledge gaps on mechanisms of photo-ionic phenomena, providing descriptors to identify materials with high photo-ionic figures of merit, and demonstrating operando light-driven nanoscale chemical manipulation. By determining materials design principles for large illumination-induced changes in kinetic and thermodynamic parameters governing ion flux, IRG2 will enable efficient, nanoscale control over ions. The resulting highly responsive photo-ionic materials will enable new electrochemical manufacturing, and energy and information technologies.