高效率雙重摻雜固態白光電化學元件

Abstract

固態白光電化學元件由於具有簡易結構、可溶液製程、可使用非活性金屬電極與低功耗等優點，在白光照明的應用上極具潛力。本文提供了一種雙重摻雜的方式來達到高效率的固態白光電化學元件，同時引入二種客體材料來改善載子平衡，因此可提升元件效率。從光激發光量測顯示出單一摻雜薄膜與雙重摻雜薄膜有相近的白色光激發光頻譜與光激發光量子產率，然而雙重摻雜元件效率高於單一摻雜元件的效率兩倍以上，因此雙重摻雜的白光電化學元件之效率提升可合理地推測為發光層內的載子平衡被改善所致。雙重摻雜元件所達之最高外部量子效率和最高功率效率分別為7.4 %與15 流明/瓦，這是目前固態白光電化學元件效率最高紀錄，因此證實了雙重摻雜的方法能有效提昇固態白光電化學元件效率。

We report highly efficient solid-state white light-emitting electrochemical cells (LECs) based on a double-doped strategy, which additionally introduces an orange-emitting guest, [Ir(ppy)2(dasb)]+(PF6─) into a single-doped emissive layer containing an efficient blue-green emitting host, [Ir(dfppz)2(dtb-bpy)]+(PF6─) and a red-emitting guest, [Ir(ppy)2(biq)]+(PF6─) to improve carrier balance and thus to enhance the device efficiency. Photoluminescence (PL) measurements show that the single-doped (red guest) and the double-doped (red and orange guests) host-guest films exhibit similar white PL spectra and comparable photoluminescence quantum yields while device efficiencies of the double-doped white LECs are twofold higher than those of the single-doped white LECs. Therefore, such enhancement of device efficiency is rationally attributed to improved carrier balance of the double-doped emissive layer. Peak external quantum efficiency and peak power efficiency of the double-doped white LECs reach 7.4 % and 15 lm/W, respectively. These efficiencies are among the highest reported for solid-state white LECs and thus confirm that the double-doping strategy is useful for achieving highly efficient white LECs.