Enhancing the Light Output-Coupling of Inverted Top-Emitting Organic Light-Emitting Diodes by Using the Localized Surface Plasmon Resonance of Ag Nanoparticles

In this study, a light out-coupling layer (LOCL) composed of Ag nanoparticles (NPs) and MoO_x is introduced on top of the inverted top-emitting organic light-emitting diode (OLED). The full width at half maximum (FWHM) is narrowed to 50 nm due to the micro-cavity effect of the top-emitting structure and the turn-on voltage is as low as 2.6 V. The AgNPs in the LOCL significantly improves the light output-coupling of the OLED owing to the localized surface plasmon resonance, and the MoO_x in the LOCL effectively protects the water- and oxygen-sensitive electron injection material. As a result, the performance of the OLED with the LOCL is significantly enhanced. The maximum current efficiency and external quantum efficiency of the device are increased by 53% and 30% to 28.27 cd A⁻¹ and 13.09%. The enhanced electroluminescent performance of the OLED, together with the narrowed FWHM and the low turn-on voltage, provides a new way to realize ultra-high-definition display and micro-display.