Abstract

Huge advances have been made in recent years in solar energy conversion from both established technologies such as silicon to emerging photovoltaics such as halide perovskites, and direct solar-to-fuel such as photoelectrochemical water splitting and CO2 reduction. Many of these technologies are either approaching their fundamental efficiency limits, or require new approaches to accelerate efficiency improvements. Here, I will present our work developing new devices based on ferroelectric-photovoltaic and ferroelectric-photocatalyst nanocomposites. Ferroelectrics produce a bulk photovoltaic effect (BPVE) that does not require a semiconductor junction therefore can produce above bandgap photovoltages. However they generally are poor light absorbers with low charge carrier mobilities. Therefore we intend to couple the BPVE with efficient photoabsorbers by intimately combining these materials in nanocomposite films. As a proof-of-concept for this effect we have combined photocatalyst materials such as Fe2O3 with porous ferroelectrics to efficiently couple the two effects together, demonstrating enhanced photocatalytic activity driven by the ferroelectric polarisation. We have also demonstrated a strain dependence of the BPVE in epitaxial BaTiO3 thin films, which has implications for optimisation of nanocomposite structures.