Efficiency improvement of organic light emitting diodes (OLEDs) using micro/nano-structures

This paper demonstrates the design of high efficiency OLEDs by incorporating micro/nano-metric structures on the surface of and inside the substrate layer of the OLEDs. The OLEDs have been designed and simulated using Lumerical FDTD simulator. We also analyze the performance of the OLEDs from various perspectives such as quantum efficiency, normalized transmitted power, intensity, and angular distribution of light. To increase light extraction from the substrate layer, various micro/nano-metric structures, made of SijN4, have been incorporated as light scattering structures. Single layer structures of various size, shape (plano-convex & plano-concave lenses and pillars), and period have been investigated during our simulation. Simulation results confirm higher light extraction, angular distribution, and efficiency in micro/nano-metric structures induced OLEDs, compared to traditional OLEDs. Plano-concave MLA engraved OLEDs show high out-coupling efficiency, whereas, nano-pillars engraved OLED shows consistent light distribution in a wide angular region. We strongly believe that, the proposed OLEDs will have wide range of commercial applications.