Nano-imprint fabrication and light extraction simulation of photonic crystals on OLED

A two-dimensional photonic crystal (PC) structure introduced into the anode layer of an organic light-emitting diode (OLED) was designed to enhance the light extraction efficiency. Using the plane wave expansion method and the finite-difference time-domain method to simulate the optical properties, we found that the extraction efficiency of the OLED device can be greatly enhanced by modifying the lattice constant of the PC array. In our simulation results, the enhancement of the extraction efficiency can approach 60% for the optimized square PC pattern with a period of ∼500nm in the OLED device emitting at the center wavelength of 510nm. In this work, the PC pattern was also fabricated to implement the simulation results via the UV-curing nano-imprint technique. To maximize the enhancement effect, the residual layer on the imprinted surface should be really thin over a large area and could thus be easily removed by the RIE process.