Improved Electroluminescence In Organic Light Emitting Diodes By Thermal Annealing Of Indium Tin Oxide Anode

摘要

We demonstrate the improved electroluminescence (EL) in OLEDs by using annealed ITO anode at different temperatures under the normal ambient. SEM studies show the smooth surface morphology of ITO film upto 300°C and it turned wrinkle kind of structure at 400°C. The hole-only device (HOD) based on ITO annealed at 300°C exhibits the higher hole-current density when compared to pristine ITO based device and it is drastically decreased for 400°C. The higher EL emission intensity was observed for OLEDs using ITO annealed at 300°C and it is drastically decreased for 400°C annealed ITO based device. These results show that the annealing of ITO anode upto 300°C improves the holeinjection in OLEDs, balancing the charge carriers and improving the device performance, whereas the change in surface properties of ITO anode annealed at 400°C in turn alters the ITO/TPD interface leading to the charge imbalance, resulting in the decreased device performances.