Tuning optoelectronic properties of ambipolar organic light-emitting transistors using a bulk-heterojunction approach

Bulk-heterojunction engineering is demonstrated as an approach to producing ambipolar organic light-emitting field-effect transistors with tunable electrical and optoelectronic characteristics. Hie electron and hole mobilities, as well as the electroluminescence intensity, cap be tuned over a large range by changing the composition of a bimolecular mixture consisting of α-quinquethiophene and N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic- diimide. Time-resolved photoluminescence spectros-copy reveals that the phase segregation of the two molecules in the bulk heterojunction and their electronic interaction determine the optoelectronic properties of the devices. The results presented show that the bulk-heterojunction approach, which is widely used in organic photovoltaic cells, can be successfully employed to select and tailor the functionality of field-effect devices, including ambipolar charge transport and light emission. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.