Brownmillerites for Photovoltaic Applications

Photovoltaics are the fastest-growing source of renewable energy generation. With conventional silicon-based solar cells starting to approach an efficiency ceiling, there is a rising demand for more efficient technologies made using sustainable materials. Photoferroic materials, with their potential for higher photovoltages, provide an alternative to conventional single heterojunction technologies in the development of next generation high-performing and cost-effective solar cells. Photoferroics that show the bulk photovoltaic effect have a non-centrosymmetric crystal structure, and require band gaps within the solar spectrum for efficient solar energy conversion.
This thesis is focused on a specific class of oxygen-deficient perovskite-related materials, called brownmillerites, and on investigating their applicability as photoferroic and conventional photovoltaic materials. Computational and experimental methods are used to identify factors that stabilise non-centrosymmetric structures, tune relevant physical properties, and confirm theoretical prediction. Prototype photovoltaic devices with brownmillerite absorber layers are fabricated and routes to optimising their performance are discussed, demonstrating their potential as sustainable and non-toxic photovoltaic materials.