Improvement of solution based conjugate polymer organic light emitting diode by ZnO-graphene quantum dots

In this paper conjugate polymer organic light emitting diode (OLED) device is improved by the insertion of electron transport layer of zinc oxide-graphene quantum dots (QDs). Prior to device fabrication, ZnO-graphene QDs thin film is thoroughly characterized by X-ray diffraction, X-ray photoelectron spectroscopy and field emission scanning electron microscopy. Aluminum is employed as the cathode of the device while ITO is used as the anode. Conjugate polymer layer of Poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) and Poly[ 2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] are used as hole injection layer and emissive layer respectively. The device performance is analyzed by the current-voltage method. The hybrid OLED is showing four times higher current densities and improved turn on voltage of 2.5 V while the device without QD has turn on voltage of 3.5 V. Improvement of luminance is achieved by the insertion of QD layer at color coordinates of (0.56, 0.43).