Materials design and interface engineering for high performance polymer solar cells

Our effort in improving the performance of photovoltaic materials and devices have been focused on two areas: modification of the interfaces between the active layer and electrodes in both conventional and inverted photovoltaic structures to improve the electrical coherence at interfaces; development of low bandgap pi-conjugated polymers with high charge carrier mobility for efficient bulk-heterojunction solar cells. In this talk, we will review our recent progress using functional self-assembled monolayer (SAM) to form dense assembly on metal oxide electrode as an interfacial layer for polymer solar cells. With appropriate choice of SAMs, a significant improvement in device characteristics can be achieved and leading to highly efficient devices. We also developed a series of low bandgap metallated conjugated polymers composed of fused thiophenes and benzothiadiazole as donor-acceptor pair in the polymer backbone and their performance as photovoltaic materials will be discussed.