Annealing effect of gold thin films on the light output performances of organic light emitting diodes

Gold thin films (GTFs) are transferred onto a nanostructured surface and their effects on the characteristics of organic light emitting diodes (OLED) are investigated. GTF deposition is realized by the physical vapor deposition technique under high vacuum. Globose gold nanostructures are successfully generated by annealing GTFs at different temperatures. Atomic force microscopy reveals morphological changes affected by film thicknesses and annealing temperatures. In the tailored device architecture, GTFs, [poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene are used as a hole injection layer, a hole transport layer, and an emissive layer, respectively. The performances of the fabricated OLEDs are enhanced in the presence of gold nanostructures obtained by thermal annealing GTFs coated onto the anode electrode of the devices. GTF thickness of 4.0 nm and an annealing temperature of 500 degrees C yield a nearly 2.6 times increase in the light output of the OLEDs.