Layered organic film growth by substrate temperature tuning for efficiency-enhanced OLEDs

Effects on resultant organic light-emitting device of substrate temperature during the evaporation process of a light-emitting material are reported. Light-emitting diodes are based on a novel bis-imido-phenylene vinylene (ImPV) derivative as green-emitting molecule. It is reported that the substrate temperature has a great influence on the thin film morphology. Heating the substrate results in a more ordered film. Using this technique, molecules of ImPV self-organise in an even layered film with 1.7 nm-thick molecular layers. Devices based on heated substrates exhibit higher operating voltages but enhanced quantum and luminous efficiencies.