Alexander Cherlin

Robert Hoye is an Associate Professor of Materials Chemistry at the University of Oxford, where he is also a Fellow of St. John’s College. He also holds the Science & Technology Facilities Council / Royal Academy of Engineering Senior Research Fellowship to develop and scale Bi-based materials for X-ray imagers, working together with the Rutherford Appleton Laboratory. Prof. Hoye completed his PhD at the University of Cambridge (2012-2014), followed by a postdoc at MIT (2015-2016), before returning to the University of Cambridge as a College Research Fellow (2016-2019). In 2020, he moved to Imperial College London as a Lecturer, then Senior Lecturer (Aug. 2022 -). In Oct. 2022, he moved to Oxford as Associate Professor. Prof. Hoye’s group focuses on developing inorganic semiconductors for energy applications, including metal-halide perovskite nanocrystals, and discovery of lead-free perovskite-inspired materials. His group’s research spans from fundamentals (including spectroscopy and computations) to materials synthesis and applications in photovoltaics, light-emitting diodes and detectors. More information: hoyegroup.web.ox.ac.uk

Prof. Hoye was awarded the 2021 Imperial President’s Award for Outstanding Early Career Researcher, as well as the 2024 RSC Beilby Medal and Prize. He is CTO of NanoPrint Innovations Ltd., which is commercialising spatial atomic layer deposition for precision manufacturing of oxide thin films.

Abstract:
Bismuth-Based Materials for Ionising Radiation Detection

Bismuth-based compounds have recently gained attention as strong attenuators for ionizing radiation detection, which occurs as a result of their high atomic number [1]. Here, I will cover our work with Bi-based materials for X-ray detectors [2, 3]. For BiOI, we use a combination of spectroscopy and first-principles calculations to show that electron-phonon coupling gives rise to a non-radiative loss channel that limits charge-carrier diffusion lengths. But these are overcome with the application of an electric field, such that mobility-lifetime products on the order of 10^-3 cm² V^-1 are achieved in the out-of-plane direction. BiOI single crystals exhibit high sensitivities of 10³ μC Gy_air^-1 cm^-2 and limits of detection <20 nGy_air [2]. The high performance is realized as a result of the low defect density in these single crystals, however, single crystals are prepared using slow methods with low yields. With Cs₃Bi₂I₉, we demonstrate an approach to scale up synthesis by having an ambient method to synthesise nanocrystals at scale. We demonstrate devices with 9 cm² area thick films that exhibited a limit of detection of 66 nGy_air s^-1, still well below the current medical standard of 5500 nGy_airs^-1 for commercial a-Se materials [3].