Nanoscale Ferroelectric-Semiconductor Coupling for Enhanced Photovoltaic and Photocatalytic Devices

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 conversion 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. The Schockley Queisser limit defines the maximum theoretical efficiency of a junction-based photovoltaic (or photochemical) device. Ferroelectric and other non-centrosymmetric materials are able to produce a 'bulk' photovoltaic effect (BPVE) that does not require a semiconductor junction, therefore in principle are not subject to the Schockley Queisser limit. However, in reality they demonstrate low power conversion efficiencies as ferroelectrics are generally poor light absorbers and charge transporters.

I will present an overview of our work to overcome these limitations by drawing on the ability of the BPVE to couple to other materials, such as semiconductor absorbers, at the nanoscale. By producing nanocomposite films combining ferroelectrics with semiconductor light absorbers we show that the photocurrent in the semiconductor can be tuned via coupling to the ferroelectric polarisation. I will show proof of concept of this principle for solar fuel applications using semiconductor photocatalysts integrated with nanoporous ferroelectrics, and for ferroelectric-photovoltaics using epitaxial nanocomposite films produced using pulsed laser deposition and perovskite solar cells incorporating nanostructured ferroelectrics.