Félix Fernandez-Alonso - Exploring (and taming) hybrid perovskites for photovoltaics – a journey through space & time

Widely regarded until a decade ago as mere academic curiosities because of their rather exotic ‘ionic-plastic-crystal’ character, hybrid (organic-inorganic) perovskites have become one of the most promising platforms for the development and subsequent deployment of next-generation
photovoltaic & photonic technologies. Yet, to date, controlling their stability remains an unresolved challenge, deeply rooted in the richness & complexity of their physico-chemical behaviour in both stable and metastable phases. In this talk, I will present ongoing efforts using
radiation-scattering techniques and first-principles computational materials modelling across the phase and compositional diagrams of the two most-celebrated hybrid perovskites – methylammonium & formamidinium lead-iodide. In particular, state-of-the-art neutron-scattering
techniques pave the way for a detailed exploration of these fascinating materials over a wide range of spatial and (quite uniquely) temporal scales. Key to the above is a detailed scrutiny of the dynamic structure factor along with the use of this fundamental experimental observable to
benchmark and validate plausible computational models. This model-selection approach is providing fresh insights into a number of pressing questions in the midst of the ongoing ́hybrid-perovskite fever, ́ including: the nature of the local structure in the ordered phases and its impact
on thermophysical properties; pathways to amorphization and decomposition; or the mechanisms of stabilization in solid solutions involving different organic cations. In closing, I will also illustrate how this combined experimental-computational methodology is being extended to other
condensed-matter systems for energy and sustainable applications.