Given the unprecedented demand for mobile capacity beyond that available from the RF spectrum, it is natural to consider the infrared and visible light spectrum for future terrestrial wireless systems. Wireless systems using these parts of the electromagnetic spectrum could be classified as nmWave wireless communications system in relation to mmWave radio systems and both are being standardised in current 5G systems. TOWS, therefore, will provide a technically logical pathway to ensure that wireless systems are future-proof and that they can deliver the capacities that future data intensive services such as high definition (HD) video streaming, augmented reality, virtual reality and mixed reality will demand. Light based wireless communication systems will not be in competition with RF communications, but instead these systems follow a trend that has been witnessed in cellular communications over the last 30 years. Light based wireless communications simply adds new capacity - the available spectrum is 2600 times the RF spectrum. 6G and beyond promise increased wireless capacity to accommodate this growth in traffic in an increasingly congested spectrum, however action is required now to ensure UK leadership of the fast moving 6G field. Optical wireless (OW) opens new spectral bands with a bandwidth exceeding 540 THz using simple sources and detectors and can be simpler than cellular and WiFi with a significantly larger spectrum. It is the best choice of spectrum beyond millimetre waves, where unlike the THz spectrum (the other possible choice), OW avoids complex sources and detectors and has good indoor channel conditions. Optical signals, when used indoors, are confined to the environment in which they originate, which offers added security at the physical layer and the ability to re-use wavelengths in adjacent rooms, thus radically increasing capacity. Our vision is to develop and experimentally demonstrate multiuser Terabit/s optical wireless systems that offer capacities at least two orders of magnitude higher than the current planned 5G optical and radio wireless systems, with a roadmap to wireless systems that can offer up to four orders of magnitude higher capacity. There are four features of the proposed system which make possible such unprecedented capacities to enable this disruptive advance. Firstly, unlike visible light communications (VLC), we will exploit the infrared spectrum, this providing a solution to the light dimming problem associated with VLC, eliminating uplink VLC glare and thus supporting bidirectional communications. Secondly, to make possible much greater transmission capacities and multi-user, multi-cell operation, we will introduce a new type of LED-like steerable laser diode array, which does not suffer from the speckle impairments of conventional laser diodes while ensuring ultrahigh speed performance. Thirdly, with the added capacity, we will develop native OW multi-user systems to share the resources, these being adaptively directional to allow full coverage with reduced user and inter-cell interference and finally incorporate RF systems to allow seamless transition and facilitate overall network control, in essence to introduce software defined radio to optical wireless. This means that OW multi-user systems can readily be designed to allow very high aggregate capacities as beams can be controlled in a compact manner. We will develop advanced inter-cell coding and handover for our optical multi-user systems, this also allowing seamless handover with radio systems when required such as for resilience. We believe that this work, though challenging, is feasible as it will leverage existing skills and research within the consortium, which includes excellence in OW link design, advanced coding and modulation, optimised algorithms for front-haul and back-haul networking, expertise in surface emitting laser design and single photon avalanche detectors for ultra-sensitive detection.

Chemical biology is the scientific discipline that harnesses the ability of small molecules to perturb biological processes. It is used to improve our understanding of those biological processes, to identify the genes that control them and to discover novel compounds that can be used to improve human health or increase crop productivity. Whilst chemical biology is widely exploited in other fields, and despite its proven power as a gene discovery tool in plants, it has been slow to gain acceptance amongst plant biologists. A primary reason for this is that the methods previously available to screen small molecules for their effects on the plant phenotype are laborious and limited in the number of traits they can monitor. At Lancaster University a novel technology has recently been developed that for the first time allows Arabidopsis seedlings to be grown under conditions suitable for studying the effects of small molecules on the development of both roots and shoots. However, it is still a laborious process to screen more than a few hundred molecules using the current version of this technology, and there are some intrinsic problems that preclude reliable quantitative analysis of root architecture. In this 15 month multidisciplinary project, a team of biologists, engineers and computer scientists will address these problems to develop the 'Microphenotron', a robotic version of the phenotyping system that will automate the process of image capture and analysis. The development of the Microphenotron will greatly expand the accessibility and utility of chemical biology approaches to the wider plant biology community, leading to a greater understanding of plant gene function. It will also provide a new tool for the development of synthetic and natural molecules for improved agricultural sustainability, with resulting benefits for farmers, the environment and society.

Seismic hazard assessment and understanding of continental deformation are hindered by unexplained slip-rate fluctuations on faults, associated with (a) temporal clusters of damaging earthquakes lasting 100s to 1000s of years, and (b) longer-term fault quiescence lasting tens to hundreds of millennia. We propose a new unified hypothesis explaining both (a) and (b), involving stress interactions between fault/shear-zones and neighbouring fault/shear-zones; however key data to test this are lacking. We propose measurements and modelling to test our hypothesis, which have the potential to quantify the processes that control continental faulting and fluctuations in the rates of expected earthquake occurrence, with high societal impact. Our aspiration is that cities and critical facilities worldwide will gain additional protection from seismic hazard through use of the calculations we pioneer herein. The background is that slip-rate fluctuations hinder understanding because they introduce uncertainty about whether specific faults are active or not. For example, a review in Japan of earthquake risk to critical facilities, such as the Tsuruga nuclear power plant (NPP), revealed a geological fault under a nuclear reactor (Chapman et al. 2014). The question that arose was whether the fault was active or not. Japan's Nuclear Regulatory Authority (NRA) has guidelines defining fault activity, and considered the fault under the reactor to be active, evidenced by faulting in sediments <~125,000 years in age. The Japan Atomic Energy Power Company (JPAC) disagreed, following study by an independent team of geoscientists. In 2014, the Tsuruga NPP remained closed due to ongoing debate between the NRA and JPAC, with similar debates ongoing for other NPPs. We suggest that defining fault activity as simply "active" or "inactive" is unsatisfactory because it is debatable even amongst experts. In fact a fault that has not slipped in many millennia may, in reality, not be inactive, but instead may simply have a low slip-rate, with the capability to host a damaging earthquake after a long recurrence interval. Our breakthrough is we think slip-rate fluctuations over both timescales (a and b) are a continuum, sharing a common cause involving interaction between fault/shear-zones. For the first time, we provide calculations that describe this interaction, quantifying slip-rate fluctuations and seismic hazard in terms of probabilities. We show that slip during an earthquake cluster on a brittle fault in the upper crust occurs in tandem with high strain-rate on the viscous shear-zone underlying the fault. This deformation of the crust produces changes in differential stress on neighbouring fault/shear-zones. Viscous strain-rate is known to be proportional to differential stress, so, given data on slip-rate fluctuations one can calculate changes in differential stress, and then calculate implied changes to viscous strain-rates on receiver shear zones and slip-rates on their overlying brittle faults. We provide a quantified example covering several millennia, but lack data allowing a test over tens to hundreds of millennia. If we can verify our hypothesis over both timescales, through successful replication of measurements via modelling, we will have identified and quantified a hitherto unknown fundamental geological process. We will study the Athens region, Greece, where a special set of geological attributes allows us to measure and model slip-rate fluctuation over both time scales (a and b), the key data combination never achieved to date. We know of no other quantified explanation that links slip-rate fluctuations over the two timescales; the significance and impact of accomplishing this is that it has the potential to change the way we mitigate hazard for cities and critical facilities. Chapman et al. 2014, Active faults and nuclear power plants, EOS, 95, 4

Solar cells are an effective way to reduce greenhouse gas emissions from the generation of electricity. Apart from contributing to the major societal challenge that climate change poses, organic solar cells (OSCs) have many exciting new applications resulting from their remarkable physical properties that sets them apart from other solar cell technologies. Their mechanical flexibility allows the integration in wearable textiles and electronic appliances, lightweight and semitransparent designs allow the deployment and retrofitting as facades for greenhouses, and low costs combined with efficient indoor operation makes OSCs feasible to supply low-power sensors for the internet of things (IoT). Overall, OSCs offer a cost-effective, scalable, and environmentally friendly way of generating renewable energy. Wide commercial success of OSCs requires further improvements in efficiency, and a stronger focus in research on industrially relevant technologies. The proposed research will identify and improve critical physical processes in OSCs. The applied materials are highly relevant to industrial production. I thereby pursue pathways to break today's limits in power conversion efficiency (PCE) and seek to push the commercialization of the technology. To identify routes towards real-world economic impact, it is worth looking at the precedent established by organic light emitting diodes (OLEDs). The commercial success of OLEDs was stimulated by so-called 'small molecules' that offer reproducible synthesis and purification, as well as longterm device stability over several years. Similarly, small molecules (SMs) rather than polymers are the most likely material choice for upscaled industrial OSC production. In terms of device function, OSCs apply an intimately mixed blend of two molecular species to generate electrical power from incoming light. The complex influence on the efficiency by the structural arrangement of molecules relative to each other is a flourishing field of research. Recently, the intermixing of the two species has been identified as the key structural property to affect OSC performance. The proposed research focuses on polymer-free All-Small-Molecule OSCs (ASM-OSCs). The core objective of my work is to build quantitative models that relate the mixing behaviour in an OSC blend to its optoelectronic properties and the resulting performance. From there, guidelines for the design of novel molecules and the deposition process are drawn and put into practice. Central to achieving these objectives are advanced optoelectronic measurements to characterize the energetic landscape and the transport and recombination dynamics of charge carriers. The holistic study of ASM-OSCs deposited from solution and in vacuum yields comprehensive and widely applicable quantitative descriptions of structure-function-performance relationships. The developed models, guidelines, and improved efficiency contribute to the advancement of solution- and vacuum processed OSC technology. Both deposition routes are highly relevant to industrial production. The proposed work will result in unprecedented high PCEs for ASM-OSCs and thereby facilitate the technology's commercial success. Ultimately, the undertaken research aims at reducing global CO2 emissions to tackle climate change, and to foster manufacturing and innovative applications in the UK and worldwide. The Department of Condensed Matter Physics at the University of Oxford offers the ideal environment for my research with excellent facilities for optoelectronic characterization and outstanding fabrication tools such as the EPSRC-awarded national thin-film cluster. National and international partners from academia and industry will support my research through synchrotron-based structural characterization, ultrafast spectroscopy, molecular simulations, synthesis of new molecules, and identification of ways to transfer research findings into commercial applications.

The capture and management of ions in water systems are of widespread importance to society. One of the most prominent applications is water desalination, which is becoming an increasingly important technology due to population growth and climate change putting pressure on freshwater resources. In recent years, capacitive de-ionisation (CDI) has gained increasing attention as a potentially low-energy alternative to more common desalination methods such as reverse osmosis. CDI works by passing a saline solution through an electrochemical cell where the positive and negative salt ions are immobilized on the surfaces of oppositely-charged porous carbon electrodes. One of the advantages of CDI over other desalination methods is that following the initial ion capture step, the electrode can be regenerated by discharging into a separate effluent stock. In this step, some of the energy used for the ion capture is recovered, and furthermore, the efficient regeneration of the electrode reduces fouling. Despite the promise of CDI, its efficiency reduces at high salt concentrations. In this respect, it does not compete with other methods such as reverse osmosis for treatment of seawater. In recent years there have been considerable research efforts to extend the concentration range in which CDI is effective. Most development has focused on optimisation of materials and cell designs with considerable success, yet, surprisingly little consideration has been given to details of the the ion behaviour or the elementary processes taking place at each electrode. One of the primary considerations is to ensure that ionic charge is stored by ions being captured by the electrode, rather than being exchanged with those in the feed electrolyte (which does not reduce the salt concentration). This proposal seeks to develop a mechanistic understanding of CDI and apply this knowledge to control the ion storage mechanism to optimize the salt removal efficiency. This will be done through the use of detailed electrochemical analysis and the use of nuclear magnetic resonance (NMR), which allows us to "see" and count ions that are captured in the electrode, and correlate this with the electrochemical response and salt removal efficiency. We will investigate how the electrode pore size and electrolyte properties, such as concentration and the nature of the ions present, affect how they are captured. This information will then be used to inform and optimise the cell design and operational conditions (e.g., flow rate and cell voltage). Our proposed work is necessarily fundamental in nature with the key aim of improving the understanding of the underlying science of CDI, rather than fabrication of prototype CDI stacks. However, through our collaborations with academic and industrial partners, we aim to work with, and identify, scalable and commercially-relevant electrode materials.