Localized and guided electroluminescence from roll printed organic nanofibres

Here, we report localized, polarized and waveguided electroluminescence (EL) from well aligned organic nanofibres integrated via roll printing on transistor platforms. The localized emission is due to the application of an alternating current voltage to the transistor gate electrodes, which causes sequential injection of holes and electrons into the organic material with subsequent charge carrier recombination and light emission from a small area near the metal-nanofibre interface. The polarization results from the mutually parallel ordering of the molecular constituents, in which the emitting dipole is oriented along the long molecular axis. Furthermore, their morphology enables the nanofibres to operate as optical waveguides and part of the generated light is therefore guided along the nanofibre and radiated at the nanofibre end. In addition to the 'standard' hexaphenylene nanofibres, we also demonstrate that this scheme can facilitate EL from a nanofibre made from a different type of molecule with altered spectral characteristics. The realization of an electrically biased organic nanoscale light-emitter demonstrates the ability to fabricate on-chip light sources with a tunable emission spectrum via synthesis of appropriate molecular building blocks.