Scalable low-cost organic photovoltaic devices

The displacement of CO2 emissions by renewable sources of energy critically depends upon the development of low-cost and widely accessible routes to clean energy generation. Solution processed organic solar cells based upon nanostructured donor-acceptor heterojunctions are currently attracting significant interest for this purpose. Substantial advances in the performance and efficiency of organic photovoltaic devices have been reported in recent years. This project focuses on three key challenges for the translation of these lab-scale efficiencies into, low cost, scalable photovoltaic device technologies. Specifically, the three aims of this project are: (i) development of indium and PEDOT -free transparent conducting electrodes which are compatible with high device-module efficiencies and cost effective scale up and (ii) development of new synthetic methods for the scale-up of high-performance organic semiconductors and (iii) the implementation of these materials into OPV modules fabricated employing processing methodologies compatible with high through put, low cost manufacture. To address these aims we have assembled a highly multidisciplinary team comprising academics and industries with world-leading expertise in inorganic oxide electrode film deposition, polymer synthesis, processing, thin-film printing, functional characterization, nanomorphology, device physics and manufacturing. This proposal builds directly on the substantial advances made in our Stage 1 Grand Challenge in Nanotechnology and Energy program funded by EPSRC, targeting the demonstration of a commercially viable production process for OPV devices with enhanced stability and reduced cost.

This proposal directly addresses three research themes indentified in the call issued on the 27th August 2010. Specifically, these themes are: (i) demonstration of scale-up in a representative environment for solar energy harvesting solution of organic solar cells (ii) development of novel materials and coatings for longitivity in service and (iii) technologies that can address the built environment sector. The environmental and social benefits of photovoltaic energy generation are well understood and abundantly clear. In this regard, developing renewable energy technologies that serve to shift our dependence away from fossil fuels could lead to a reduction in CO2 emissions. The scientific, technological and industrial impact of this project is also clear. For example, the solar industry is one of the fastest growing, with between 30-50% year-on-year growth in installed capacity. Current installed global photovoltaic capacity is ~23 GW. This is expected to continue into the near future with projections of up to 50% yearly growth in installed capacity to 2014 (Global Market Outlook for Photovoltaics Until 2014, EPIA, May 2010). To maintain this level of growth new technologies are now required that address issues of, cost of manufacture, to allow large area depositions, and/or high module efficiency. In this regard, the low-cost and organic photovoltaic architectures of the nature that are proposed in this project exhibit significant potential advantages over existing PV technologies. For instance, one of the key challenges facing to design of scaleable OPV devices is the almost exclusive dependence of ITO as the electrode material of choice where the high cost and scarcity of indium prohibits scale-up and widespread use. The successful execution of this project will lead to new electrodes that are indium-free compatible with large area device manufacture. Commercial exploitation pathways are in place through the direct involvement of industrial partners in this project (Pilkington, RK-print, Flexink and NPL). For example, the ability to scale the manufacture of OPV technology to large areas fits into the NSG Group expertise and on-going strategy. The company currently holds a leading position in the Global thin film photovoltaic market as a supplier to the PV element industry. The NSG Group is ideally positioned to supply substrates to new market opportunities with new glass coating facilities about to become on-stream in the UK and elsewhere around the world. Flexink are an SME specialty chemicals company, with expertise in high purity ready to use organic semiconductor ink development, and will scale up synthesis of the donor polymers utilising the new tin free routes. Our other industrial partner RK-print specializes in equipment for the controlled application of surface coatings onto substrates and has expertise in the printing of polymer films of optoelectronics. As such, RK-print is well positioned to work with members of the consortium to research and develop the equipment required for large area printing of organic photovoltaics and will be uniquely able to exploit any demand for printing equipment that arises from this project.