摻入金奈米海膽於有機發光電化學元件以電漿增益提升電致發光效率

Abstract

固態有機發光電化學元件因為展現許多優點如:簡單的元件結構、低操作電壓、在大氣中相對穩定之元件電極，所以使其受到學界廣泛的注目，為了近一步改善元件特性，我們展示了以摻入金奈米海膽於有機電化學元件之陽極中，藉由表面電漿共振效果來提升電致發光之效率。因為金奈米海膽的效果，較薄元件的峰值效率可以被提升35%，然而金奈米海膽卻無法提升較厚元件的電致發光增益，其原因為較厚元件其複合區落在金奈米海膽之近場範圍外，因此挑選適合的發光層厚度將會是實現有機電化學元件其電致發光之電漿增益的關鍵。再者薄元件由於激子猝熄造成的電致發光損耗可以從金奈米海膽的電漿增益來復原，在薄元件與厚元件比較中可以發現薄元件在峰值光輸出功率約有73%之提升，而且兩者的元件效率維持在相同的大小，藉由摻雜金奈米海膽在薄元件中可以同時實現更高的光輸出亮度和元件效率，這些結果顯示摻雜金奈米海膽於元件陽極中來改善有機發光電化學元件是一個簡單且可行的方法。

Solid-state light-emitting electrochemical cells (LECs) have received intense scientific attention since they show advantages of simple device structure, low-voltage operation and compatibility with air-stable electrode metals. To further improve device performance, enhanced electroluminescence (EL) from localized surface plasmon (SP) resonance in LECs incorporating gold nanourchins (NUs) at the anode is demonstrated. With gold NUs, 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 recombination zone in thicker LECs is located outside the near-field range from gold NUs. Therefore, choosing proper 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 LECs incorporating gold NUs. These results reveal that incorporation of gold NUs at the anode would be a simple and feasible way to improve device performance of LECs.