含有嵌入式紅光色彩轉換層之白光電化學元件

Abstract

本篇論文中以嵌入式光色轉換層的方式來達到高效率的白光電化學元件，其結構為在藍綠光材料為主體的發光元件外側加入高效率的紅光轉換層，紅光轉換層吸收主動層發出的藍綠光後放出高效率紅光，藍綠光和紅光混合後產生出白光。實驗中選擇具有高光激發光效率的紅光材料，其吸收帶與藍綠光材料所產生的電激放光波帶有著很好的重疊，少量摻雜紅光材料至光色轉換層可使其自我猝熄的機率降低，相對地提高元件的效率。嵌入式結構為優化2012年Su與Wu等人提出的外掛式色彩轉換層白光元件，根據元件內部模態理論，因嵌入式光色轉換層是直接將紅光轉換層放在元件內部，故可將元件出光內部中最大的模態損失"波導模態"取出利用，進而提高元件的發光效率。電性量測到本元件架構高達12.5 %的外部量子效率及26流明/瓦的功率效率，此效率為目前文獻中最高效率的有機電化學白光元件。

Highly efficient white light-emitting electro chemical cells (LECs) are realized by employing an embedded red color conversion (CCL) between the blue-emitting emissive layer and the substrate. White emission is composed of the blue electroluminescence (EL) and the red photoluminescence (PL) resulted from absorption of the blue EL in the CCL and subsequent energy transfer. The efficient red-emitting dye is properly chosen to exhibit significant spectrum overlap band of the blue EL. Low doping concentration of the red dye in the CCL is beneficial in reducing self-quenching effect, enhancing device efficiencies. Compared to previously the proposed embedded CCL structure can make use of blue EL in the wave-guiding mode. Thus, the device efficiency of white LECs can be significantly improved the peak external quantum efficiency and power efficiency achieved in the white LECs with and embedded CCL are as high as 12.5 % and 26 lm/W, respectively. These efficiencies are among the highest reported in white LECs.