Light extraction enhancement in organic light-emitting diodes based on localized surface plasmon and light scattering double-effect

Abstract

We have demonstrated a new approach to realize the light extraction enhancement in organic light-emitting diodes (OLEDs) by using platinum–cobalt (Pt₃Co) alloy nanoparticles (ANPs). The current efficiencies of 19.2 cd A⁻¹ and 29.3 cd A⁻¹ at a current density of 20 mA cm⁻² are obtained for the device with Pt₃Co ANPs unannealed and annealed, respectively, which correspond to a ∼46% and ∼123% enhancement compared to the control device without Pt₃Co ANPs. A systematic study on the devices with and without unannealed Pt₃Co ANPs shows that the significantly enhanced efficiency is mainly due to the resonance of localized surface plasmon (LSP). The analysis of surface topography, angular-dependent EL spectra and theoretical calculations of the devices with and without annealed Pt₃Co ANPs reveals that the annealing treatment of Pt₃Co ANPs could result in a further enhancement in light extraction due to the increased light scattering effect, thereby achieving a double-enhancement in light extraction by simultaneously realizing the resonance of LSP and the light scattering effect.