Supervisor: Dr Paul Shaw, COPE

Abstract: The next generation of solar cells based on organic semiconductors can be solution processed over large areas leading to panels that are cheaper than current technology as well as being lighter and flexible. Current state-of-the-art performance for organic solar cells is 16%, which has been achieved through the development of new materials and improved device architectures. Photocurrent generation requires the dissociation of a tightly bound excitonic state into free charges. This process occurs via an intermediate charge-transfer (CT) state and is surprisingly efficient given the high binding energies involved. This project will develop the experimental capability to optically detect CT-states in working organic solar cells with high sensitivity external quantum efficiency measurements. This is a critical development as the CT-state is difficult to probe and as a consequence its precise role is poorly understood. To further help elucidate the physics of the charge generation process a diverse range of innovative materials (non-fullerene acceptors, high-dielectric constant materials) developed within the Centre for Organic Photonics & Electronics will be employed. The outcomes from this project will provide a powerful new perspective with which to understand organic solar cell performance and advance the technology.