利用共摻雜電子傳輸層材料於發光層提升三波段白光磷光有機發光二極體特性

研究中利用高電洞遷移率的主發光體材料(TCTA)與電子遷移率較佳的電子傳輸層材料(TmPyPB)，以共摻雜方式來製作藍光OLED元件之混合式主發光體結構(mixed-host structure)，提升電荷載子注入到發光層的效率，降低元件驅動電壓，並提升元件發光效率，利用CsF取代LiF作為電子注入層與調整摻雜的濃度比例(1:1)至元件最佳化後，藍光元件於亮度1000 cd/m2時，驅動電壓降為4.4 V，電流效率提升到34.7 cd/A，功率效率增加至24.8 lm/W。研究亦利用將橘紅光材料(Os(bpftz)2(PPh2Me)2)摻入最佳化藍光元件內的不同位置，可製作高效率雙波段白光元件，實驗結果顯示，當Os與FIrpic共摻雜於單發光層(TCTA：TmPyPB)時，於亮度1000 cd/m2時，元件驅動電壓為4.6 V，電流效率由34.7 cd/A提升到37.4 cd/A，功率效率由24.8 lm/W增加至25.5 lm/W。實驗最後於混合式主發光體結構中，共摻雜Os(bpftz)2(PPh2Me)2、Ir(ppy)3與FIrpic，並調整三色摻雜物之摻雜區位置以製作三波段白色磷光OLED元件，當發光層結構為RGB共摻雜時，可有效改善元件色偏(color-shift)之問題，其元件搭配BEF，於發光亮度1000 cd/m2下，電流效率為43.8 cd/A，功率效率為32 lm/W，且最大電流效率可達45.4 cd/A及功率效率為35.7 lm/W，且當元件操作電壓由4 V至8V，其1931 CIEx,y座標CIE值由(0.346, 0.374)僅偏移至(0.316, 0.364)。

關鍵字

混合式主發光體結構；電荷載子平衡；高效率；磷光白光有機發光二極體

並列摘要

In this study, the hole transport-type host material (TCTA) was incorporated with the electron transport material (TmPyPB) as a mixed-host structure to future improving the injection of charge carriers and reduce the driving voltage of the phosphorescent organic light-emitting diodes (PHOLEDs). The charge carrier balance of PHOLED was achieved by using CsF as electron injection layer and optimizing the doping ratio of TCTA and TmPyPB (1:1). At a luminance of 1000 cd/m2, highly efficiency blue PHOLED shown the best yield of 34.7 cd/A and power efficiency of 24.8 lm/W. Furthermore, a highly efficiency two-components system white PHOLED can be obtained by doping Os(bpftz)2(PPh2Me)2 into the emitting layer of optimizing blue PHOLED. The driving voltage of 4.6V, yield of 37.4 cd/A, and power efficiency of 25.5 lm/W at a luminance of 1000 cd/m2 can be obtained. Finally, a high efficiency three-components system white PHOLED was fabricated by co-doping three phosphor dopant (Os(bpftz)2(PPh2Me)2, Ir(ppy)3 and FIrpic) into mixed-host (TCTA:TmPyPB) structure and optimizing the doping region and each layer thickness. From the experimental results, the optimal white PHOLED showed the driving voltage of 4.4 V, yield of 34 cd/A, and power efficiency of 24.2 lm/W at a luminance of 1000 cd/m2 can be observed. Furthermore, the efficiencies can be increased to 43.8 cd/A and 32 lm/W by attaching an outcoupling brightness enhancement film (BEF) onto glass substrate and the CIE coordinate exhibited blue-shift from (0.346, 0.374) to (0.316, 0.364) under different driving voltages.