The case for supporting clean, renewable technologies is strong with UK Government commitments to ensuring 15 % of our energy comes from renewable sources by 2020, this represents a seven fold increase in the market share for renewables in less than a decade. This target can only be achieved by implementing a combination of complementary solutions including biomass, wind, wave and solar. In particular solar energy harvesting has the potential to become competitive, in both economic and performance terms, if current limitations associated with next generation technologies can be overcome. In addition to environmental benefits there is the potential for significant economic development, recent analysis suggests that the entire renewable energy sector could support up to half a million jobs in the UK by 2020. The demand is present, evidenced by the increase in UK PV capacity from 10.9 Mw in 2005 to an estimated 26.5 Mw in 2009. Inorganic-organic hybrid photovoltaic (h-PV) devices are a realistic prospect for the long-term development of entirely solution processable, scalable devices on rigid and flexible substrates. The pairing of a metal oxide (TiO2, ZnO) with a conjugated polymer to form a hybrid device is an attractive combination of materials. For example, ZnO provides efficient electron mobility, effective light-scattering, is of low cost and can be formed in a wide variety of (nano) structures from aqueous solution. The absorbing, hole-transporting conjugated polymers, such as poly(3-hexylthiphene)(P3HT), support a wide variety of processing routes and exhibit some of the best charge transport of all organic semiconductors. However progress made towards realising such h-PV technologies has been slow. Reported power conversion efficiency (PCE) values are typically < 1%, with some more recent publications reporting 2%. This compares with reported efficiencies of > 8% for commercial organic-PVs. The nanostructured devices that will be prepared in this program will provide controlled bicontinuous networks for charge, and importantly will allow control of the polymer morphology - a parameter that has received little attention in h-PVs - although it is known to strongly influence exciton generation, free carrier transport and light absorption. This unique combination of materials and processing strategies presents an exciting opportunity for the development of h-PV devices that can overcome the current performance limitations by allowing control of the structural and morphological properties of the device not possible with other material combinations or processing techniques.

The design and construction of an ideal material for organic semiconductor devices requires the careful consideration of a range of physical properties. In some cases, what would represent good materials characteristics for one type of device may be highly detrimental to the efficiency of another. Intermolecular pi-pi interactions symbolise one good example: in organic light emitting devices, photoluminescence is quenched by these attractions and the device efficiency is reduced dramatically; in organic field effect transistors (OFETs), it is desirable to promote pi-pi interactions throughout the bulk, so that charge mobility can be maximised. In this proposal, we aim to prepare materials for organic photovoltaic (OPV) devices and OFETs. The novelty in this work originates from very recent results, in which we demonstrate that highly soluble materials with conformational freedom in solution are able to self-assemble in the solid state to give highly planar and conjugated structures. Such levels of planarity, which maximise the possibility of pi-pi interactions, have only been achieved previously with ladder or ribbon type structures which possess inherent solubility problems. In our systems, long range planarity can be achieved through the use of weak, non-covalent interactions; to date, this approach has not been given significant consideration and is therefore waiting to be exploited.

The design and construction of an ideal material for organic semiconductor devices requires the careful consideration of a range of physical properties. In some cases, what would represent good materials characteristics for one type of device may be highly detrimental to the efficiency of another. Intermolecular pi-pi interactions symbolise one good example: in organic light emitting devices, photoluminescence is quenched by these attractions and the device efficiency is reduced dramatically; in organic field effect transistors (OFETs), it is desirable to promote pi-pi interactions throughout the bulk, so that charge mobility can be maximised. In this proposal, we aim to prepare materials for organic photovoltaic (OPV) devices and OFETs. The novelty in this work originates from very recent results, in which we demonstrate that highly soluble materials with conformational freedom in solution are able to self-assemble in the solid state to give highly planar and conjugated structures. Such levels of planarity, which maximise the possibility of pi-pi interactions, have only been achieved previously with ladder or ribbon type structures which possess inherent solubility problems. In our systems, long range planarity can be achieved through the use of weak, non-covalent interactions; to date, this approach has not been given significant consideration and is therefore waiting to be exploited.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The development of cheap renewable energy sources is required to reduce the environmental effects associated with the use of conventional fossil fuel based energy sources. Of all the renewable energy technologies, solar energy has the greatest potential as a world power source. For this reason, solar photovoltaic (PV), the direct conversion of sunlight to electricity, is expected to play a significant role in future electricity supply. Here we focus on the development of photovoltaic devices based upon organic semiconducting materials. This project focusses on two issues that are widely recognized as being key for the development of low-cost efficient and stable photovoltaic devices: (i) the development of low cost alternatives to indium tin oxide (ITO) as the transparent conducting electrode and (ii) control of nanomorphology of the donor-acceptor interface. This project will involve the design and synthesis of new electrode materials and the use of molecular self-organization strategies to control the donor-acceptor film morphology at the nanometre length scale to deliver high efficiency organic solar cell that are capable of being scaled up cost effectively. This project will also lead to an improved fundamental understanding of device function. This multidisciplinary project brings together chemists, physicists, materials scientists and engineers with world-leading expertise in metal oxide electrode design, polymer synthesis and manufacturing. This project also involves collaboration with Pilkington Glass, Merck Chemicals and BP Solar.