白光磷光有機發光二極體效率提升之研究

Performance Improvement in White Phosphorescent Organic Light-Emitting Diodes

何育宇(Yu-Yu Ho)

指導教授 ： 莊賦祥

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2011年)

摘要

本研究是探討利用單極性電洞傳輸特性之主發光體材料(TCTA)與電子傳輸材料(3TPYMB)，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並利用其載子傳輸特性及能階的差異，藉以將載子再結合區侷限於TCTA與3TPYMB之混合式主發光層，以降低元件驅動電壓，並提升元件發光效率。另外，亦於電洞傳輸層(TAPC)與發光層之間，加入一電洞遷移率小於TAPC且具有電洞傳輸特性之主發光体材料 (TCTA)，作為中間層(interlayer)以增加電洞注入至發光層的數量，並搭配CsF取代LiF做為電子注入層，使發光層內的載子更為平衡，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。結果顯示，最佳化藍光元件結構於發光亮度1000 cd/m2下，驅動電壓降低至4.15V，電流密度為2.98 mA/cm2 ，發光效率提升至36 cd/A，功率效率可達27.5 lm/W。研究亦利用將橘紅光材料(Os(bpftz)2(PPh2Me)2)共摻雜摻於最佳化藍光元件之混合式主發光層內，以得到高效率白色磷光有機發光二極體。結果顯示，白光有機發光二極體在亮度為1000 cd/m2時，驅動電壓為4.38 V，發光效率為36.1 cd/A及功率效率達26.4 lm/W。另外，於ITO玻璃基板出光面搭配一增亮膜，增強白光元件發光特性，使白光元件效率於亮度1000 cd/m2提升至46.7 cd/A及34.27 lm/W，其最大元件效率為49.84 cd/A及43.3 lm/W。

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

Highly-efficiency white phosphorescent organic light emitting diode (PHOLED) can be achieved by using mixed-host structure and doping red phosphor into emission layer. In this study, we utilizes the hole transport-type host material (TCTA) was incorporated with the electron transport material (3TPYMB) 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). In addition, a hole transport-type host material (TCTA) was inserted between HTL and EML as interlayer to enhance hole injection due to reduce the barrier between HTL and EML and further increased the luminance efficiency. The charge carrier balance of PHOLED was achieved by using CsF as electron injection layer and optimizing the doping ratio of TCTA and 3TPYMB (1:1). Experimental results had showed that for the blue OLED with brightness of 1000 cd/m2, the driving voltage was 4.15 V, luminance efficiency 36 cd/A, and power efficiency reached 27.5 lm/W. Finally, a high efficiency three-components system white PHOLED was fabricated by co-doping two phosphor dopant (Os(bpftz)2(PPh2Me)2 and FIrpic) into mixed-host (TCTA:3TPYMB) structure and optimizing the doping region and each layer thickness. From the experimental results, the optimal white PHOLED showed the driving voltage of 4.38 V, yield of 36.1 cd/A, and power efficiency of 26.4 lm/W at a luminance of 1000 cd/m2 can be observed. The optimum white PHOLED with brightness enhancement film at a luminance of 1000 cd/m2 shown yield of 46.7 cd/A, and power efficiency of 34.27 lm/W was observed. Furthermore, the white PHOLED with the max luminance efficiency 49.84 cd/A and the max power efficiency 43.3 lm/W.

並列關鍵字

mixed-host structure ； charge carrier balance ； high efficiency ； phosphorescent organic light-emitting diode

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