Directly Imprinted Periodic Corrugation on Ultrathin Metallic Electrode for Enhanced Light Extraction in Organic Light-Emitting Devices

A micro/nano structure on the metallic electrode is necessary to outcouple power lost to surface-plasmon polaritons (SPPs) in organic light-emitting devices (OLEDs). However, a simple and efficient method to integrate the micro/nano pattern onto the surface of the metallic film is still a challenge. In this work, thermal nanoimprint lithography has been employed to directly imprint periodic corrugation onto an ultrathin metallic film. Both surface morphology and conductivity of corrugated metallic film have been improved by the imprinting process, which is important for its use as electrode in optoelectronic devices. The photons that trapped in SPP modes associated at the organic-cathode interface in the OLEDs have been efficiently extracted by using the periodically corrugated ultrathin metallic film as anode of the OLEDs. A 56% enhancement of current efficiency was achieved compared with the planar device. The corrugated ultrathin anode is further applied to flexible OLEDs, and improved light extraction efficiency has been obtained.