Electroluminescence of ZnO nanorods/MEH-PPV heterostructure devices

ZnO nanorods are synthesised by a hydrothermal method on ITO glass. Then ITO/ZnO/ZnO nanorod/MEH-PPV/Al heterostructure devices are fabricated. Under DC bias, ultraviolet (UV) electroluminescence (EL) at 380 nm from ZnO band edge emission is observed. In addition, exciton emission of MEH-PPV at 580 nm and defect related emission of ZnO nanorods at 640 nm and 747 nm are also detected. Upon increasing the applied voltage, the UV EL becomes predominant and is much stronger than other emissions at 28 V. The mechanisms of ZnO band edge emission and background emission are discussed.