In order to reduce CO2 emissions and thus limit global warming we need to reduce energy consumption. One way to do this is to make the machines that we use in everyday life, ranging from car engines to washing machine motors and bearings, more efficient. This is particularly important since there is a huge rate of growth in the use of machines in countries such as China and India as these become more prosperous. There are several strategies for increasing machine efficiency but one of the most effective is to reduce mechanical friction. So far this has been done mainly by using lower viscosity lubricants, which have less friction drag. However, this approach is reaching the end of its usefulness since, it also leads to thinner fluid films between rubbing surfaces, which eventually results in high wear as well as even more friction. The solution now lies in improving the performance of surfaces films, which can protect components and reduce friction regardless of lubricant viscosity. These are called boundary films, and must be made to form more quickly and durably, and give lower friction. This is currently impossible since, despite a century of research and widespread commercial use, there is inadequate understanding of the mechanisms by which they form. The biggest gap in our understanding concerns the way that the rubbing process stimulates film formation. When solids are rubbed together actual contact occurs only at a few high spots on the surfaces. The conditions at these contact points are extremely severe, with very high local stresses which plastically deform the rubbing surfaces. Under such conditions, a phenomenon called "triboemission" occurs; i.e. fundamental particles such as electrons, ions and photons are ejected from the surfaces. These energetic particles promote a series of chemical reactions in the lubricant present that leads, ultimately, to the formation of protective boundary lubricating films. These particles can also have harmful effects such as causing lubricant film degradation on computer hard drives. In order to improve boundary film formation we need to understand triboemission and its effect on lubricants. Unfortunately these processes occur between a pair of rubbing surfaces, where it is difficult to see and measure. Furthermore, particles emitted react almost instantly with the lubricant present, and are obscured by the competing influences of frictional heating and extreme pressure. This makes research on triboemission very challenging to carry out, which is why we currently know so little about it. The research group which I aim to build will develop and apply a series of novel experimental techniques to study triboemission and to monitor its impact on lubricants and boundary film formation. The key is to look at each stage of the emission and film formation process and link these together. Particle detection apparatus will be built and incorporated into friction testing equipment. Thermal mapping will be used to distinguish triboemission from other causal factors, while fluorescence imaging (currently used mainly in biomedical applications to study molecule mobility) will help track transient reaction species in the lubricant. Additionally, the application of scanning probes will pioneer the mapping of emission and allow correlation with surface properties. In this way, the series of interactions that occur between lubricant and environment will be unravelled. With industrial support, this understanding will be used to design enhanced surface and lubricant combinations. The result will be improved friction performance and, in certain critical applications, protection of the lubricant from degradation. This summary has focussed on engineering contacts but triboemission is also believed to play a decisive role in the lubrication of bio-contacts and micro-contacts, where friction is a significant factor in performance. These applications will also be studied in my research.

Photovoltaic (PV) solar cells now generate a significant proportion of the world's electricity and have vast potential for further growth. PV is enormously important to the UK with >13.5 GW now installed here, and growth worldwide is forecast to be over tenfold in the next three decades. More than 90% of solar cells are produced from crystalline silicon, and costs have fallen to levels not previously thought possible (< 2.34 US cents/kWh). Other technologies have yet to gain industrial traction and commercial barriers to entry are becoming substantial. Silicon-based solar technology is hence likely to remain dominant and critical to the expansion of renewable energy in the coming decades. Its continuous advancement is essential to accelerate uptake of and impact from green electricity generation worldwide and for fulfilling the UK's obligations under the Paris Agreement. The passivated emitter and rear cells (PERC) architecture is standard for today's silicon solar cells. The PERC technology will reach its practical limits in the next 10 years, with a top forecast commercial efficiency of ~24%. Overcoming this efficiency boundary requires cell architectures that circumvent the limitations of PERC. This project aims to develop a new cell technology to supersede PERC in which the drawbacks of high temperature processing are avoided, the efficiency potential of a single junction is fully exploited, and a route to implement tandem and bifacial architectures is directly possible. This programme brings together teams at the Universities of Oxford and Warwick with world-leading expertise in silicon surface passivation, carrier lifetime, and impurity management for the development of PV devices. The aim is to conduct fundamental work necessary to facilitate a step-reduction in the cost per Watt of PV electricity, thus producing a disruptive change in the advancement of this important renewable energy industry. This project will develop a charged oxide inversion layer (COIL) solar cell by integrating advanced nanoscale thin-film materials to augment the PV potential of a silicon absorber. This novel cell architecture has the potential to overtake the current standard PERC devices, while providing a direct route to use in emerging selective contact, tandem, and bifacial designs. So far, the efficiency of an inversion layer architecture has been exploited only to a limited extent, e.g. in a 18% cell. The potential of the COIL cell extends well beyond this mark, and as high as 28% in a single-junction configuration could be achieved. This project will deliver the fundamental understanding necessary to unlock this potential, exploit the inversion layer concept by engineering highly charged dielectric thin-films, and use these films to produce a prototype cell device.

Hybrid polaritonics combines the properties of different light emitting materials - organic polymers and semiconductors - in order to produce quasiparticles that combine the possibilities of both systems. "Polaritons" are quasi-particles that arise from strong coupling between light and matter. This means that they have hybrid properties, combining the mobility and flexibility of light, with the possibilities of interactions due to the matter component. At high enough densities, or low enough temperatures, polaritons can form a macroscopic coherent quantum state, a polariton condensate, or a polariton laser. Such a coherent state shows much of the same physics as Bose Einstein Condensation, as has been seen for cold atoms, but without requiring the ultra-low tempeatures required for atoms. Hybid polaritonics focuses on how, by combining different "matter" parts of the polariton, one can push these temperatures even higher, up to room temperature, and how one can engineer completely tunable system. The matter part of a polariton can come from any material which will absorb and emit light at a specific wavelength. Much existing work on polaritons is based on the material being inorganic semiconductors. These can be grown controllably, and one can drive such devices by passing an electrical current through them to make a polariton laser. However, the coupling between matter and light in semiconductors is not strong enough for these devices to work at room temperature. In contrast, organic molecules and polymers can show huge coupling strengths, but are generally poor electrical conductors. Our programme is to combine the benefits of both systems to provide a whole set of devices, operating at room temperature, based on the formation of polaritons. These devices will range from polariton lasers (providing a route to easily tunable lasers with very low threshold currents), to Terrahertz light sources (with applications in non-invasive medical imaging and explosives detection), to ultra-efficient light emitting diodes. To reach these ambitious objectives, we need to combine expertise from a wide number of fields. Our team contains world experts in light emitting polymers, semiconductor growth, characterisation and spectroscopy of polaritons, and in theoretical modelling. Members of our team have previously achieved the first realisations of polariton lasing, of strong coupling with organic materials, and of building hybrid polariton lasers. The possibility to combine this expertise draws on the unique strengths that the UK currently has in this area, and enables the combination of this expertise to be focussed on providing room temperature devices based on hybrid polaritonics, and to revolutionise this field.