Enhancement of Light Extraction Efficiency of Organic Light Emitting Diodes using Spin-on Glass based Randomly Dispersed Nano-pillar Arrays

Abstract

Randomly dispersed nano-pillar array (RaDNA) was embedded between the transparent electrode and the glass substrate to extract lights confined inside organic light emitting diodes (OLED). The room-temperature nano-imprining lithography (RT-NIL) was employed for the fabrication of RaDNA. Spin-on glass was utilized as a material of the nano-pillar array for stable devices. The pillar arrays were planarized before fabrication of OLEDs using a high refractive index material (trialkoxysilane-capped PMMA-titania hybrid optical material) to reduce the leakage current. The RaDNA OLED showed 7% enhancement in normal direction and 19% enhancement of light extraction efficiency in an integrating sphere. The emission pattern of RaDNA device showed no variation of emission spectrum with azimuthal angle and viewing angle.