Enhanced light extraction from green organic light-emitting diodes by attaching a high-haze random-bowls textured optical film

Random-bowls textured (RBT) optical film with high optical haze (∼96%) possessing strong scattering ability is attached directly to the glass substrate exterior of organic light-emitting diodes (OLEDs) in order to improve the light-extraction efficiency of the OLEDs. The power and current efficiency of OLEDs with RBT film are improved by 27.2% and 26.3%, respectively, compared with the reference OLED without RBT film. Additionally, the EL spectrum of the OLEDs remains stable with the usage of the RBT optical film and change of visual angle. We confirm that the optical film can change the light traveling path due to its random-bowls structure and improve the extraction of a part of the light confined into the substrate by ray-tracing optical simulation. The utilization of RBT optical film with high haze is a simple and promising approach to enhancing light-extraction efficiencies of OLEDs.