Defects by Design; Understanding and Controlling Defect Processes in Advanced Energy Materials

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There is an urgent demand for next-generation energy materials which can provide the necessary cost decreases and performance boosts to create a sustainable green economy. Using a high-throughput computational materials modelling strategy, we aim to enhance the performance of relevant energy materials, namely photovoltaic solar cells, batteries and thermoelectric, via the controlled implementation of crystalline defects.When the body creates billions of genetic code in DNA, there are inevitable imperfections termed genetic mutations. Likewise, there are similar inevitable imperfections in every solid-state material which can significantly enhance or degrade device performance, such as solar cell efficiency, battery capacity and battery lifetime. However, it is challenging to identify the specific defects which improve performance or trigger degradation and efficiency reduction. Modern defect theory provides a powerful tool for understanding and controlling defects in crystals (predicting concentrations and transport rates) and in interpreting experimental probes of defect processes, including activation energies for diffusion, and electronic/vibrational/spin signatures. In this project, we will develop a novel software infrastructure for the characterisation of defects in crystalline solids and predicting signatures for direct comparison between modelling and experiment. Specifically, the computational approach of hybrid Density Functional Theory (DFT) will be implemented to investigate the defect chemistry of relevant energy materials, through the calculation of defect formation energies, characterisation of defect core levels and identification of stable oxidation states. The insights gained from this work will be applied to the cutting edge of solid-state energy material research and development, optimising energy device performance and cost by providing design strategies to overcome current limitations. Predictions will be validated with experimental partners at Cambridge, Imperial College London and UCL. Moreover, this research will provide a novel framework for in-depth high-throughput investigations of defects in solid-state materials, which will prove a valuable research community tool for defect design applicable to other materials systems. This project is most relevant to the EPSRC research theme of 'Energy', specifically the research areas of 'Materials for Energy Applications', 'Energy Storage' (both of which are classified as target areas for growth in EPSRC investment), in addition to the area 'Condensed Matter: Electronic Structure' in the 'Physical Sciences' theme.