PV materials that can be processed from solution at low temperature offer a route to low cost and low emebedded energy PV modules with potential for integration into buildings and other infrastructure to generate clean electricity on a large scale. Organic PV (OPV) has attracted intense research interest; impressive improvements in efficiency and in fabrication knowhow have been demonstrated. Lead halide perovskites solar cells (PSC) are based on a newly rediscovered active layer material and have shown radical improvements in start-of-life efficiency with recent optimisation of device structure and processing. However both technology types are challenged by losses in power conversion efficiency under operation, even though they are believed capable of stabilised efficiency of 15-20%. The limited operational stability of such devices inhibits their widespread commercial application. To overcome this there is a need to understand the sources of efficiency loss, both at start-of-life and during ageing in typical operating environments. Until now, most studies of novel PV device stability have amounted to empirical studies of the evolution of performance parameters for different materials or device structures in different environments, and scientific attention has focussed largely on the oxidative stability of the photoactive layer. Relatively little attention has been paid to the electrodes and interlayers, even though these layers are often the first to fail and additionally they are partly responsible for protecting the active layers. In addition, most performance metrics probe the macroscopic device performance and although imaging methods have been used to observe heterogeneous material properties during ageing mapping techniques have not yet been used to provide detailed insight into the chemical, electrochemical and physical mechanism of current and voltage loss. This proposal seeks to develop a set of interlinked experimental techniques to probe the basic mechanisms underpinning device degradation and failure in two leading classes of printable photovoltaic (PV) materials, organic photovoltaics (OPV) and organohalide perovskite solar cells (PSCs). Our approach is to develop and adapt two-dimensional mapping techniques that probe the local chemical and electronic state of the materials and combine them with device-scale electrical measurement, structural characterisation and modelling in order to analyse the degradation mechanisms, to identify the local conditions that lead to degradation and to design strategies to inhibit the progression of failure mechanisms. The mapping tools will be developed with the potential to be applied during module manufacture and quality control.

Solar is an increasingly important source of power generation. Word-wide installations of new solar modules will exceed 40GW in 2014 with over 1GW that capacity will be installed in the UK. The cost of modules has decreased sharply over the past two years due to over-supply from manufacturers. The cost reduction is now stimulating demand because the cost of energy from solar is now at 'grid parity' in some important regions of the world. An exciting new type of solar cell based on thin film perovskite light absorbers has been discovered in the UK which has the potential to lower costs still further. The discovery has been made by a team of researchers at Oxford University. The progress they have made with these new devices has been unprecedented and in only two years the Oxford team has achieved conversion efficiencies exceeding 17%. Moreover, the technology has been protected by filing patent applications on the fundamental discoveries. The Supergen Supersolar Hub comprises eight of the UK's leading University groups (including Oxford) engaged in the development of photovoltaic technologies. The Supergen SuperSolar Hub was quick to recognise the importance of the perovskite development and has already funded complementary research programmes in Hub member and Associate member laboratories through its flexible funding. This proposal for Supergen + funding will increase the scope and ambition of the Hub's perovskite research in modelling, synthesis, process optimization and characterization to boost conversion efficiencies still further and help maintain the UK's leadership position. In addition to the proposed research, proposals are made to increase the Hub's involvement with industry and with leading International laboratories to accelerate progress and lay the foundations for timely exploitation.

Light emitting semiconductor materials and devices dominate many aspects of everyday life. Their influence is all pervasive providing the sources which enable the internet, large area displays, room and street lighting to give just a few examples. Their existence relies on the high quality semiconductor structures which may be prepared by advanced crystal growth and sophisticated nanofabrication. Our proposal aims to capitalise on the advanced growth and fabrication to achieve similar advances in the quantum world where often counter-intuitive behaviour is governed solely by the laws of quantum mechanics. Our overall aim is to explore the behaviour of nano-devices operating in regimes where fundamentally new types of quantum-photonic phenomena occur, with potential to underpin the next generation of quantum technologies. We focus on two complementary systems: III-V semiconductors with their highly perfect crystal lattices, proven ability to emit photons one by one and long coherence quantum states, and atomically-thin graphene-like two dimensional (2D) semiconductors enabling new band structures, stable electron-hole bound states (excitons) and easy integration with patterned structures. The combination of the two material systems is powerful enabling phenomena ranging from the single photon level up to dense many-particle states where interactions dominate. A significant part of our programme focusses on on-chip geometries, enabling scale-up as likely required for applications. The semiconductor systems we employ interact strongly with photons; we will achieve interactions between photons which normally do not interact. We will gain entry into the regime of highly non-linear cavity quantum electrodynamics. Excitons (coupled electron-hole pairs) and photons interact strongly, enabling ladders of energy levels leading to on-chip production of few photon states. By coupling cavities together, we will aim for highly correlated states of photons. These advances are likely to be important components of photonic quantum processors and quantum communication systems. In similar structures, we access regimes of high density where electrons and holes condense into highly populated states (condensates). We aim to answer long-standing fundamental questions about the types of phase transitions that can occur in equilibrium systems and in out-of-equilibrium ones which have loss balanced by gain. We will also study condensate systems up to high temperatures, potentially in excess of 100K, and of the mechanisms underlying phase transitions to condensed states. The condensed state systems, besides their fundamental interest, also have potential as new forms of miniature coherent light sources. Nanofabrication will play a vital role enabling confinement of light on sub-wavelength length scales and fabrication of cavities for photons such that they have very long lifetimes before escaping. The ability to place high quality emitters within III-V nanophotonic structures will receive enhancement and potential world lead from a crystal growth machine we have recently commissioned, specially designed for this purpose, funded by the UK Quantum Technologies programme. Similar impact is expected from our ability to prepare 2D heterostructures (atomically thin layers of two separate materials placed one on top of the other) under conditions of ultrahigh vacuum free from contamination, enabling realisation of bound electron-hole pair states of very long lifetime, the route to condensation to high density states. The easy integration of 2D heterostructures with patterned photonic structures furthermore enables nonlinear and quantum phenomena to be studied, including in topological structures where light flow is immune to scattering by defects. Taken all together we have the ingredients in place to achieve ground-breaking advances in fundamental quantum photonics with considerable potential to underpin next generations of quantum technologies.

We propose a Centre for Doctoral Training in New and Sustainable PV. It will support the transformation of PV in the UK will that will in turn aid the country to achieve its renewal energy obligations, and will generate jobs in the technology sectors as well as local manufacturing and installation. The CDT allows for the distributed nature of PV research in the UK with a multi-centre team of seven partners covering all aspects of PV research from novel materials through new device architectures to PV systems and performance. The PhD projects and training span engineering and physical science expertise in materials and device physics, electronic engineering, physical and synthetic chemistry, operations management and manufacturing. The CDT graduates will be capable of transforming state of the art R&D across the PV technologies and, in so doing, contribute to the production and implementation of improved PV products and systems. All partners are members of the SuperSolar Hub and hence already coordinate integrated PV research and training. Students in the CDT will join a thriving research community. The team has unrivalled access to shared facilities in the best state of the art laboratories in the UK. Our group approach brings together expertise with a breadth and depth for training and research that could not be assembled in any other way. Moreover, the collaboration allows us to cut across the traditional boundaries in PV and enables exciting research vectors to be followed in New and Sustainable PV CDT agenda. International collaborations and formal exchange agreements will emphasise the global aspects of advanced research that are important for the development of a leadership group. The CDT members will interact with related research themes such as photochemical conversion of fuels for energy and other applications, and heating and cooling by solar radiation and will be a proactive member of the UK wide Network of Energy CDTs. Our goal is to train the best researchers with a flexible mindset able to communicate across different disciplines and be leaders in the emerging PV industry for advanced technologies. We will provide the training required for graduates to join the sustainable energy and PV sectors. We will establish a real identity of purpose and commonality in each cohort through a training programme designed to give students an understanding of all aspects of PV, including implications for society and an experience of a commercial environment. Students will be provided with a bespoke curriculum and training programme that exposes them to: (i) underpinning fundamentals across all the relevant disciplines, (ii) current state-of-the-art in knowledge and challenges in scale-up and systems, and (iii) unparalleled opportunities to engage in leading-edge interdisciplinary research projects as part of a national team. We will create a doctoral training environment in which students benefit from leading academic expertise and world-class facilities to develop their knowledge as well as the tools to innovate and create within their selected research theme. The unique cross functional skill-sets that our graduates will have will make them highly valuable to the academic community seeking to address ambitious basic manufacturing research challenges, and to industry, who have an urgent need for appropriately trained scientists and engineers able to support PV technologies within their commercial operations. To allow the students the chance to develop a common sense of purpose, each cohort will attend training events together. Courses will cover fundamental aspects common to all PV technologies and also advanced courses based on the partners' research expertise. There will be industrial and international placements. Coherence across the CDT will be aided by a virtual collaboration medium containing webinars and video lectures and pages where students and staff can collaborate via groups, and online forums.

Solar photovoltaic (PV) technology is becoming a major source of renewable energy around the globe, with the International Energy Agency predicting it to be the largest contributor to renewables by 2024. This uptake is driven by the building of large PV power plants in regions of high solar resource, and also by the deployment of so-called distributed PV on the roofs of homes and industrial sites. The dominant PV technology to date has been based upon the crystalline semiconductor silicon. The production of silicon PV panels has been commoditised for large-scale manufacturing with costs reducing by a factor of ten in under a decade. Our research addresses the next generation of printed PV technologies which could deliver solar energy with far greater functional and processing flexibility than c-Si or traditional compound semiconductors, enabling tuneable design to meet the requirements of market applications inaccessible to current PV technologies. In particular, we seek to advance photovoltaics based upon organic and perovskite semiconductors - materials which can be processed from solution into the simplest possible solar cell structures, hence reducing cost and embodied energy from the manufacturing. These new technologies are still in the early stages of development with many fundamental scientific and engineering challenges still to be addressed. These challenges will be the foci of our research agenda, as will the development of solar cells for specific applications for which there is currently no optimal technological solution, but which need attributes such as light weight, flexible form factor, tuned spectral response or semi-transparency. These are unique selling points of organic and perovskite solar PV but fall outside the performance (and often cost) windows of the traditional technologies. Our specific target sectors are power for high value communications (for example battery integratable solar cells for unmanned aerial vehicles), and improved energy and resource efficiency power for the built environment (including solar windows and local for 'internet of things' devices). In essence we seek to extend the reach and application of PV beyond the provision of stationary energy. To deliver our ambitious research and technology development agenda we have assembled three world-renowned groups in next generation PV researchers at Swansea University, Imperial College London and Oxford University. All are field leaders and the assembled team spans the fundamental and applied science and engineering needed to answer both the outstanding fundamental questions and reduce the next generation PV technology to practise. Our research programme called Application Targeted Integrated Photovoltaics also involves industrial partners from across the PV supply chain - early manufacturers of the PV technology, component suppliers and large end users who understand the technical and cost requirements to deliver a viable product. The programme is primarily motivated by the clear need to reduce CO2 emissions across our economies and societies and our target sectors are of high priority and potential in this regard. It is also important for the UK to maintain an internationally competitive capability (and profile) in the area of next generation renewables. As part of our agenda we will be ensuring the training of scientists and engineers equipped with the necessary multi-disciplinary skills and closely connected to the emerging industry and its needs to ensure the UK stays pre-eminent in next generation photovoltaics.