Etch-less UV-NIL process for patterning photonic crystal structure onto OLED substrate

An etch-less ultraviolet nanoimprint lithography (UV-NIL) process is proposed for patterning a photonic crystal (PC) structure onto an organic light-emitting diode (OLED) substrate. In a conventional UV-NIL, anisotropic etching is used to remove the residual layers and to transfer the patterns onto the substrate. The proposed process does not require an etching process. In the process, a stamp with nano-scale PC patterns is pressed on the dispensed resin and UV light is then exposed to cure the resin. After tens of seconds, the stamp is separated from the patterned polymer layer on the substrate. Finally, high-refractive index material is coated onto the layer. The refractive index of the polymer should be very similar to that of glass. The enhancement of the light extraction was assessed by the three-dimensional (3D) finite difference time domain (FDTD) method. The OLED was integrated on a nanoimprinted substrate and the electroluminance intensity was found to have increased by as much as 50% compared to a conventional device.