The role of an interfacial layer in transport characterization of organic photovoltaic polymers and devices

Organic electronics materials are finding broad applications in the state-of-the-art optoelectronic devices. Examples are mini-displays in digital cameras, cell phones, flexible displays, ultra-thin and high contrast TV, and more recently as tablet PC. For applications in displays and in photovoltaic, controlling the motions of charge carriers, i.e. electrons and holes, within the device is essential. Balancing electron and hole currents avoids the accumulation of space charges and is beneficial to the operations of both organic light-emitting diodes and organic photovoltaic (OPV) cells. However, for the study of charge transport of organic photonic materials, it is necessary to delineate the separate contribution of each kind of carrier in the overall current flow. This proposal outlines schemes of tuning the charge injection into organic photonic materials via a charge blocking or trapping layer. In this way, truly unipolar devices can be constructed for reliable measurements of carrier transport parameters. The outcome of this proposal should lead to better understanding of charge transport in organic photonic materials. Finally, we point out how carrier transport parameters can be correlated to device performance in an OPV cell