Perovskite solar cells are the fastest growing solar technology in history, with demonstrated power conversion efficiencies exceeding 23%, above established solar technologies such as polycrystalline silicon, CIGS or CdTe. The main advantage of perovskites is their ease of processing, i.e. they can be printed from simple inks, and their elements are in abundance; ensuring their long-term low cost. This results in very high-quality materials that can also be applied in lighting applications such as general room lighting, displays for hand-held devices and larger screens and communication devices. It is highly unusual that low-cost materials that can efficiently convert light to electricity can also efficiently do the reverse process of electricity to light. Manufacturing these kinds of materials does not require the expensive high-tech infrastructure currently needed to make electronic components. This makes this family of materials extremely attractive for many important technological sectors beyond solar energy. The main aim of our project is to improve the performance and stability of perovskite solar cells by introducing a novel layered perovskite material to extract charge from the device. This approach removes the requirement to employ very expensive organic layers currently in use and will lead to significant further cost-savings, making the technology more attractive for commercial enterprises. To achieve this, our project aims to introduce moisture barrier layers that can efficiently allow electrical current flow only in one direction through them based on perovskite ``quantum-well'' structures, i.e. very thin sheets of the perovskite material (several atom layers in thickness) that are sandwiched between equally thin plastic sheets. By carefully selecting the appropriate plastic sheet material, the structure becomes more resistive to water, and thus more stable, while maintaining the high-quality electronic properties of the perovskite family. By developing these novel structures, our project will enable the manufacture of new types of electronic devices beyond solar cells. For instance, materials that show quantum-well properties are very useful for the fabrication of lasers. These are integral to information technologies and are also used in many other applications that could be even more widespread if they were sufficiently cheap.

Perovskite semiconductors are a new class of semiconductor that can be used as the active layer in photovoltaic (solar cell) devices, producing low-carbon electricity directly from sunlight. The best perovskite solar cells can now convert sunlight to electrical energy with an efficiency of over 22%, with such devices being produced using solution based techniques. Here, a perovskite 'precursor' solution can be spread over a surface which then forms the perovskite semiconductor material. This process is expected to allow perovskites to be 'printed' onto surfaces, allowing solar cells to be produced at very low cost. In this project, we will focus on the use of spray-coating to deposit perovskite solar cells. Spray-coating is routinely used to coat paints and pigments in many manufacturing processes, and critically is not restricted to coating 'flat' surfaces, but can cover curved surfaces - for example the curved roof of an automobile. We will take full advantage of this, and will make the first detailed study of the use of spray-coating to coat perovskite solar cells over non-planar surfaces, e.g. over cylinders or aerofoil-shapes (similar to the shape of an aeroplane-wing). We believe that the results of this work will form the basis of a series of new technologies. A particular focus of our work will be to use spray-based techniques to coat perovskite PV over carbon-fibre composite materials. Carbon-fibre is already widely used in industry as a high-performance, light-weight engineering material - e.g. forming the body of sports-cars, the hulls of yachts and in other demanding applications. By coating the surface of carbon-fibre with a solar-cell, we will be able to create a new class of super-strong, lightweight materials that are able to generate electricity from sunlight at low cost. We believe such materials will be of particular importance in generating power for mobile applications, and will have identified a range of applications in the aerospace and automotive sectors. To realize such a task we have assembled a team of researchers having world-leading expertise in the development of spray and deposition techniques to fabricate perovskite solar cells, together with researchers expert in the processing and testing of carbon-fibre composite materials. A key part of the project will be to understand the interactions between the different materials that we will deposit and the carbon fibre surface. We will make a full characterization of the mechanical properties of the solar-cells we develop, and will explore techniques to 'encapsulate' such devices to maximise their operational lifetime.

Future energy demand can be addressed by using renewable and inexhaustible solar energy, providing clean, unlimited, economical and green energy. The world global photovoltaic (PV) capacity currently stands at >140 GW and is expected to reach levels of 1 TW within the next decade. Electricity generation from the sun employing PV technology is currently dominated by Si-based PV and requires expensive equipment and process and schemes for cost reduction on a large scale are limited. Thin film technologies such as CdTe and Cu(In,Ga)Se2 (CIGS), provide a lower cost alternative primarily due to the use of in-line and low-temperature processes. While considerable efforts have been made to increase efficiency and reduce costs, thin film PV currently relies on scarce and therefore expensive resources and/or toxic elements. Alternative thin film materials would therefore provide routes to reduce PV cost-per-watt while still exhibiting lower input energy requirements. Solar cells based on Cu2ZnSn(S,Se)4 (CZTSSe) absorber layers offer such an alternative. Despite its young history CZTSSe record efficiency stands at 12.6% and the major limitations are (i) a lower than expected open circuit voltage accompanied by a low efficiency at converting and collecting carriers from low energy photons; (ii) the difficulty in controlling the kesterite crystal structure throughout the fabrication process; and (iii) the use of hydrazine, a highly toxic chemical, in the fabrication process to achieve the record efficiencies. This project will use nanocrystal dispersions (inks) of CZTS fabricating from hot injection as the starting material. This technique can reliably control crystal structure, composition and doping and does not present any environmental risks. Inks are easily spin coated or sprayed on substrates and a heat treatment under selenium rich atmosphere promotes grain growth without loss of the crystal structure. In order to fabricate record efficiencies using this technique the microstructure of the absorber and back contact layers need to be engineered to provide large grains extending the full thickness of the absorber combined with a small interfacial layer to ensure a good ohmic contact. This will be achieved by the removal of long hydrocarbon chained ligand in the nanocrystal fabrication alongside modifications of the selenization procedures. In addition the role of substrates and process impurities affecting devices performances will be quantified. I will produce nanoparticle inks, solar absorber and PV devices and demonstrate world leading results.

A wealth of world-leading international research is aimed at addressing the global challenges of energy (both generation and storage), climate-change and the problems associated with finding sustainable methods to meet our increasing energy demands. Much of this effort focuses on making existing technology more robust, efficient and cheaper or discovering new methods to convert, store and transmit renewable energy. For engineers, chemists, biologists and physicists working within the confines of their own research fields, it is impossible to recognise all of the key problems for given energy system. These problems present on an extremely broad range of length scales (nm-m) and consequently calls for significantly more collaboration between the physical science and engineering to transmit the success of new materials discovery and understanding of the behaviour of these new materials to achieve durable, efficient, sustainable and manufacturable energy systems. The North East Centre for Energy Materials (NECEM), formed between the universities of Newcastle, Durham and Northumbria, seeks to unite the broad range of expertise present at the three sites to tackle a grand challenge of energy materials and will make it possible to cooperate widely with local, national and international industry. The main focus of NECEM will be to address one of the most fundamentally critical elements of all energy systems, namely the interfaces between the materials within it and their interaction with the environment in which they operate. NECEM aims to be a world-leading programme on the understanding and manipulation of such interfaces in energy materials. The vision is to identify, exploring our unique blend of materials discovery, analysis techniques and energy applications new approaches operating over the full range of length scales (nm-m) that overcome existing limitations, such as corrosion, charge trapping, marine fouling. By addressing previously unexplored directions NECEM has the ability to provide an urgently needed step change in the science and engineering of materials that use, generate and store energy more efficiently. The assets of NECEM include the breadth of expertise within marine energy (tidal and wave energy), solar (photovoltaic and solar fuels by photo-electrochemistry), fuel cells (hydrogen and alcohol based, also enzymatic and microbial), energy storage (Li-Ion, redox-flow batteries), biomass (gasification, fermentation and direct conversion to heat or even electricity) and local smart grid structure (with concurrent production and consumption of renewable energy). We invite the Energy Materials community to engage with our centre to access this expertise and our unique blend of surface processing and characterization techniques distributed across the three sites. Probing and manipulating processes occurring at surfaces and interfaces is exceptionally complex but by combining our state-of-the-art facilities, which are ideal for this challenge, and our expertise in modelling behaviour in materials to compete systems, we can drive the development of new durable, efficient and sustainable energy solutions. We are geared towards cooperation with other centres in the UK in order to be able to cover a broad portfolio of all relevant energy material problems. This centre has the strong advantage of close proximity and brings together expertise from neighboring universities in the North East of England. Importantly this will enhance knowledge exchange and collaboration increasing the probability of success of the centre. It is also very attractive for additional funding both within the UK and in Europe.

Solar energy can provide both electricity and heat without greenhouse gas emissions. The amount of solar radiation incident on the roof of a typical UK home still exceeds its heating demand over the year. However, there is only 1% of renewable heat from solar currently exploited in the UK. The paramount reason for that is the seasonal mismatch between heating demand and solar thermal energy availability and the lack of extensive deployment of thermal energy storage in the UK. Secondly, because of relatively weak solar radiation being far away from equator leads to relatively low temperature heat using the existing solar thermal collectors, particularly during periods outside summer. In this case, it is imperative to develop a seasonal solar energy storage that can effectively store abundant but relatively low temperature solar heat in summer and utilise this at the desired temperature for space and hot water heating in winter, so that 100% solar fraction can be used for space and hot water 'zero-carbon' heating. Thermochemical sorption energy storage technology offers higher energy density with minimum loss due to the temperature-independent means of storage, storing energy as chemical potential. However, its desorption temperature (i.e. temperature of the energy charging process) is relatively high, which makes it problematic to recover solar energy in high-latitude regions like the UK when using the most mature and economic solar thermal collector technology (flat-plate or evacuated tube type). Therefore, an advanced hybrid thermochemical sorption and vapour compression processes is proposed in this project, the integration of the electric-driven compressor, using a small amount of electricity input, enables a large amount of low or ultra-low temperature solar heat (<50 degC) to be efficiently used for thermochemical desorption, leading to enhance the efficiency, capability and flexibility of solar energy storage and heat pumping (Solar S&HP). Since such a hybrid system utilises thermal energy and electric energy simultaneously, it is a win-win solution when it couples with a solar hybrid thermal-photovoltaic (T-PV) collector. The solar T/PV collector supplies the hybrid storage system with solar heat and electricity, whilst the timely extraction of solar heat from the hybrid solar T-PV collector also allows the PV cell to operate at a lower temperature to increase its electrical conversion efficiency, leading to substantially improved overall solar energy conversion efficiency. Some other detailed advantages of the proposed system are, (1) the quality (thermal only) and quantity of different energy inputs (both thermal and electrical) can be adjusted to complement each other whilst storing energy so as to cope with highly variable weather conditions whilst maximising solar energy conversion. Even if solar electricity is not available, electricity from the grid in summer can be used, which has a ~15% lower carbon intensity than in winter. (2) The hybrid thermochemical cycle has a lower desorption temperature which reduces sensible heat loss from the solid sorbent and metallic reactor during the energy storage process which further increases the overall energy efficiency of storage system. (3) During thermal discharging in winter: (a) primary energy consumption for heating can be eliminated, and (b) the collective effect of thermal-driven and electric-driven heat pump processes can be used in extremely cold weather conditions. The whole SSTES system can provide heating at near zero carbon intensity, its carbon emission is approximately 92% and 85% lower comparing to gas boiler and electric heat pump technology, as revealed by the preliminary calculation results.