Winner: 2024 Beilby Medal and Prize
Robert Hoye
University of Oxford
For pioneering, interdisciplinary contributions to the discovery, understanding and manufacture of defect-tolerant semiconductors for energy conversion and healthcare applications.
Some of society's greatest challenges require efficient semiconductors. These include solar cells, which convert sunlight to clean electricity, and photoelectrochemical cells, which harvest light to produce fuels without emitting greenhouse gases. However, semiconductors often have defects that waste energy and make it more expensive to produce near-perfect materials. Professor Hoye's group is working on discovering a new generation of semiconductors that can tolerate these imperfections to achieve efficient performance when manufactured cost-effectively with a low CO2 footprint. Some of the new materials his group has worked on include bismuth oxyiodide, which they have developed into solar cells, photoelectrochemical cells and X-ray detectors for safer medical imaging.
Biography
Robert Hoye is Associate Professor at the University of Oxford, where he is also a Fellow of St John's College and an STFC-RAEng Senior Research Fellow. He leads a group of four postdocs and seven PhD students, working on developing novel optoelectronic materials for energy conversion. His group has pushed forward the development of defect-tolerant semiconductors with band-like transport. They have used a combination of materials chemistry, ultrafast spectroscopy, and computations with the aim of unravelling the chemical-physical factors that enable these properties in order to design more efficient semiconductors. They have applied these materials in thin film photovoltaics for energy harvesting to sustainably power Internet of Things electronics, X-ray detectors and photodetectors, as well as artificial-leaf devices that harvest sunlight to split water into fuels. Professor Hoye originates from New Zealand, where he completed his undergraduate degree at the University of Auckland (2009–2011). He subsequently secured a Cambridge-Rutherford Memorial Scholarship to read a PhD at the University of Cambridge (2012–2014), supervised by Professor Judith Driscoll. He then moved to MIT for a postdoc, working with Professor Tonio Buonassisi (2015–2016), before returning to Cambridge as Junior Research Fellow at Magdalene College (2016–2019) and Downing College (2019–2020), hosted by Professor Sir Richard Friend. In 2018, he became a PI through the Royal Academy of Engineering (RAEng) Research Fellowship, which he initially held in Cambridge, before moving to Imperial College London as a Lecturer (2020–2022), then the University of Oxford as Associate Professor (2022–present). Professor Hoye's research is highly interdisciplinary, and he has supervised more than 15 PhD students at Cambridge, Imperial and Oxford with backgrounds in chemistry, materials science, chemical engineering and physics.
Q&A with Professor Robert Hoye
I think inverse design of materials is a fascinating challenge. This is not just about AI or automation but also about building up new fundamental insights that will guide the design of next-generation technologies. Defect tolerance is an especially exciting area and could offer a new route to achieve efficient semiconductor devices manufactured using cost-effective methods. The past decade of work on defect tolerance in metal-halide perovskites has opened up many questions, and unravelling the links between the many complex factors that influence how defects could be tolerated in materials is an important challenge for the field.
The biggest challenge was securing the first academic position and building up a research group. I first became a PI through the Royal Academy of Engineering Research Fellowship, which I initially held at Cambridge. As a new PI, two of the biggest questions are: 1) how does one create a unique research platform that is recognised as distinct from those of previous supervisors, and 2) how does one compete for bright students in an environment with many other high-profile and well-established PIs?
Fortunately, I was in a supportive environment and working across two ‘supergroups’ – the Optoelectronics Group and the Device Materials Group in Cambridge. These supergroups are comprised of multiple PIs, and I was able to use the shared equipment to conduct independent research. At the same time, the highly collaborative and supportive environment provided a vibrant ‘ecosystem’ for PhD students to thrive in, and this helped to attract talented students to work with me. After establishing a track record as an independent PI, it is always much easier to build up the research group. Getting started is always the hardest part.
A highly collaborative and supportive research environment, where people are actively working together to solve problems together and discuss science in an open way.
Bismuth is next to lead on the periodic table and has very similar physical and electronic properties, but unlike lead, it is nontoxic. As such, bismuth-based compounds are appealing for developing electronic analogues to lead-halide perovskites with the aim of replicating the exceptional optoelectronics properties of these materials, but overcome their stability and toxicity limitations.
Bismuth is also the heaviest element that is not radioactive. This makes bismuth-based compounds, such as BiOI, highly appealing for radiation detectors since the attenuation of ionising radiation depends on the average atomic number raised to the fourth power. We have demonstrated that BiOI requires lower thicknesses than industry-standard materials to attenuate sufficient radiation, which reduces the required transport distances that charge carriers need to be transported over, which contributes to the ability of these materials to very sensitively detect low dose rates of radiation. This can lead to X-ray detectors that make medical imaging safer by reducing the required X-ray dose that the patient is exposed to.
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