Organic semiconductor interfaces for molecular electronics

Organic semiconductors combine the semiconductor properties traditionally associated with inorganic materials with the more desirable properties of plastics. Moreover, the organic syntheses of these materials allow for great flexibility in the tuning of their electronic and optical properties. By combining these properties, organic semiconductors such as conjugated polymers have been demonstrated as the active material in light-emitting diodes, transistors, and photovoltaic cells. On the other hand, these conjugated polymers provide a new way of looking at many of the broad fundamental scientific issues related to using molecules for electronics, which are explored in many different materials systems down to the single-molecule scale. A great deal of the physics, which governs the behaviour of molecules for electronics, occurs at the organic-organic interfaces. Therefore, understanding of the organic interfaces is crucial to the success of molecular electronics. The organic interface study of a range of well-controlled inter-chain and intra-chain heterojunctions with different length-scales is the central theme of this proposal, with an important focus on molecular-scale electronic structures and electronic processes across these interfaces. We will first examine various organic semiconductor inter- and intra-chain heterojunctions based on conjugated polymers from micron- to molecular-scale. At these heterojunctions, we will then explore photophysical, electronic, and operational dynamics of electronic species and charge-carriers. Through this project, molecular-scale electronics will be addressed on the basis of understanding of these organic-organic interfaces.