Plasmonic enhancement in electroluminescence from light-emitting electrochemical cells incorporating gold nanourchins

Abstract

Solid-state light-emitting electrochemical cells (LECs) have received intense scientific attention since they show advantages of a simple device structure, low-voltage operation and compatibility with air-stable electrode metals. To further improve the device performance, enhanced electroluminescence (EL) from localized surface plasmon (SP) resonance in LEC incorporating gold nanourchins (NUs) at the anode is demonstrated. With gold NUs, the peak device efficiency of thinner LECs (140 nm) can be enhanced by 35%. However, gold NUs result in no enhancement in EL for thicker LECs (200 nm) since the recombination zone in thicker LECs is located outside the near-field range from gold NUs. Therefore, choosing appropriate emissive-layer thickness would be critical to realize plasmonic enhancement in EL from LECs. Furthermore, EL loss due to exciton quenching in thinner LECs can be recovered by plasmonic enhancement in EL from gold NUs. Compared to thicker LECs, up to 73% enhancement in peak light output can be achieved in thinner LECs and the device efficiency remains similarly high. Higher light output and device efficiency can be simultaneously realized in thinner LEC incorporating gold NUs. These results reveal that the incorporation of gold NUs at the anode would be a simple and feasible way to improve the device performance of LECs.