Understanding structural, optical, and thermoelectric properties of complex metal halides for energy applications

Metal Halide perovskites have recently emerged as remarkable solar energy absorbers, for example, attaining photovoltaic conversion efficiencies exceeding 25% . The leading materials in the field contain the element lead, and despite their excellent power conversion properties, are toxic and also unstable on extended use. These factors limit their commercial application. There is a significant opportunity to develop lead-free, air-stable compounds that replicate the beneficial properties of their Pb analogues, but to do this, the fundamental physics and chemistry of these compounds must be better understood. Here we propose to study complex metal halides and oxy-halides, focusing on lead-free materials that have potential applications in energy technology. The complex metal halides offer a wide parameter space; changes to chemical composition, crystal and electronic structure permit the study of composition-structure function relationships, and this acts as an ideal opportunity for interdisciplinary Physics-Chemistry research, aligning with the EPSRC Physical Sciences and Energy Themes, and specifically the areas: Advanced Materials, Condensed matter: electronic structure, and Materials for Energy Applications.
The aim of the project is to synthesise and characterise new complex metal halide materials for photovoltaic and thermoelectric applications. We seek to understand the link between chemical composition, physical properties, and function, to allow navigation of large parameter space to find exceptional materials.
The project will focus on innovative chemical synthesis of high-quality samples, for example, by vapour phase transport, solution and gel phase crystal growth, and thin film formation by physical and chemical methods. State of the art characterisation, for example, diffraction (X-ray and neutron), photoemission spectroscopy, optical characterisation using steady state and time resolved methods, will be undertaken by the student. Lastly, functional testing, for example by building photovoltaic devices, testing thermoelectric parameters, or testing materials in a photocatalytic reactor, will be carried out. Together, by linking fundamental properties, such as crystal structure, electronic structure, optical properties, transport properties to function, we will gain better understanding of these fascinating materials, and will be better placed to produce highly efficient energy materials in fields such as photovoltaics, thermoelectrics, luminescent materials and catalysts.