Solution-processed polyfluorene-ZnO nanoparticles ambipolar light-emitting field-effect transistor

We report on a solution-processed polyfluorene (PFO)-ZnO nanoparticles composite light-emitting organic field-effect transistor (LE-OFET). The behavior of absorption, photoluminescence spectra and electroluminescence intensity of the PFO:ZnO hybrid films with different concentration of ZnO nanoparticles is analyzed. By changing the PFO/ZnO nanoparticles concentration ratio the PFO: ZnO OFET shows either unipolar or ambipolar behavior of current-voltage characteristics and operates in the hole/electron accumulation mode with current saturation behavior. The field effect mobility of charge carriers depends on the ZnO concentration. For the ambipolar PFO: ZnO OFET with modest PFO/ZnO nanoparticles ratio (1:0.2), well balanced electron and hole mobility values at 300 K are similar to 0021 and similar to 0029 cm(2)/Vs, respectively, whereas for films with high ZnO concentration (1: 1) the mobility (similar to 2 cm(2)/Vs) is close to that of polycrystalline ZnO. The ambipolar PFO: ZnO LE-OFET emits light at both positive and negative gate bias. The working mechanism of the PFO: ZnO LE-OFET is investigated. (C) 2011 Elsevier B.V. All rights reserved.