採用紅光色彩轉換層製作高效率固態白光電化學元件

Abstract

本論文以外加光色轉換層的方式達成高效率的白光元件架構，在藍綠光有機電化學元件出光側加上一層高效率紅光轉換層，紅光轉換層吸收藍綠光後產生內部能量轉移而放出高效率紅光，藍綠光和紅光混合後產生白光。實驗中選擇擁有高光激發光效率的紅光材料，其吸收帶與藍綠光材料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能使其自我猝熄的機率降低，相對地提高元件效率。電性量測到本元件架構的外部量子效率峰值為5.93 %，功率效率峰值為15.34 lmW-1，此為現存文獻中最高效率的有機電化學白光元件之一，此外本元件架構由於發光層僅用單一材料，排除了多重材料摻雜的不穩定性，幾乎不會因為偏壓改變而導致色彩偏移，有著非常好的色穩定性，這是實際應用在生活中最重要的變數。實驗結果顯示利用單層有機電化學藍色光元件配合光色轉換層能有高效率、高色彩穩定性，極具實務應用的潛力。

We report efficient and color-stable white light-emitting electrochemical cells (LECs) by combining single-layered blue-emitting LECs with red-emitting color conversion layers (CCLs) on the inverse side of the glass substrate. By judicious choosing of the red-emitting dye doped in CCLs, good spectral overlap between the absorption spectrum of the red-emitting dye and the emission spectrum of the blue-emitting emissive material results in efficient energy transfer and thus sufficient down-converted red emission at low doping concentrations of the red-emitting dye in the CCLs. Low doping concentration is beneficial in reducing self-quenching of the red-emitting dye, rendering efficient red emission. Electroluminescent (EL) measurements show that the peak external quantum efficiency and the peak power efficiency of the white LECs employing red CCLs reach 5.93% and 15.34 lm W-1, respectively, which are among the highest reported for white LECs. Furthermore, these devices exhibit almost bias-independent white EL spectra, which are required for practical applications, due to nondoped emissive layers. These results reveal that single-layered blue-emitting LECs combined with red-emitting CCLs are one of the potential candidates for efficient and color-stable white light-emitting devices.