有機發光二極體(Organic Light Emitting Diode, OLED)，具有自發性、輕薄、廣視角、高對比、高反應速率、全彩化等特質，它已成功應用在手機及電視，成為新世代的主流顯示技術；而其低耗電、平面光源、高光質、光線柔和等特性，亦使它成為最具潛力的照明技術。其中，藍光在高品質全彩顯示器應用，提供色彩飽和度，使其具有更寬廣的色域；然而，藍光相對於紅光、綠光而言，其元件效率較不理想，因此提升藍光元件的效率，極為重要；這也對於攜帶型顯示器，亦是一項重大的研究。本研究利用電性模擬(SETFOS) 及元件研製，探討藍光OLED元件中，其激子再結合的差異；據此，我們分別利用兩種主體材料4,4-bis(carbazol-9-yl)biphenyl (CBP)與4,4′,4″-tris(carbazol-9-yl) triphenylamine (TCTA)，並摻雜天藍光染料；以及電子傳輸材料bathophenanthroline (Bphen) 和 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) ，互相搭配組合。結果顯示，使用主體CBP與Bphen的組合，和TPBi相比時，有最好的元件表現；其能量效率從2.4提升至12.5 lm/W，增幅為23.8%；電流效率從2.9提升至12.4 Cd/A，增幅為30.5%；外部量子效率從1.2提升至5.1 %，增幅為30.8%；並且，再結合率從6.5×101提升至3.5×106 cm-3s-1，增加105倍。此良好的元件表現，可歸因於Bphen 具有 (1) 較深的最低未填滿分子軌域（Lowest Unoccupied Molecular Orbital, LUMO） (-2.9 eV) 降低電子注入主體CBP的能障，使載子較為平衡的注入；(2) 較深的最高填滿分子軌域（Highest Occupied Molecular Orbital, HOMO）(-6.3 eV)，使得電洞有效的侷限在發光層中，增加有效的再結合區；(3) 較高的電子遷移率，使在相同電壓時，較TPBi有更有效的電子傳輸，增加發光層中再結合機率，提升元件表現。

Organic Light-Emitting Diode (OLED) has the characteristics of spontaneity, light-ness, wide viewing angle, high contrast, high reaction rate, and full color. It has been successfully applied to mobile phones and televisions, becoming the mainstream of the new generation. Moreover, it’s low power consumption, flat light source, high light quality, soft light, and other characteristics make it becoming the most potential lighting technology. However, blue light is used in high-quality and full-color dis-play applications to provide color saturation, which makes it have a wider color gamut; however, the efficiency of the blue device is less than the red and green device, so the improvement of the blue device efficiency is extremely important. In the pre-sent work, we used electrical simulation (SETFOS) and device fabrication to inves-tigate the role
of charge-transporting materials on exciton recombination and electric field distribu-tion across the emissive and electron-transporting layers in blue OLED devices. The devices are composed of two host materials 4,4-bis(carbazol-9-yl)biphenyl (CBP) and 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), doped with blue-light dyes; batchhenanthroline (Bphen) and 2,2',2" -(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) as electron materials. The outcome is CBP:Bphen has the best performance compared with TPBi as ETL; the power efficacy is increased from 2.4 to 12.5 lm/W, an increment is 23.8%; current efficacy is increased from 2.9 to 12.4 Cd/ A, an increment is 30.5%; external quan-tum efficiency is increased from 1.2 to 5.1%, an increment is 30.8%; also, the re-combination rate increased from 6.5x101 to 3.5x106 cm-3s-1, is greater than CBP:TPBi composed 105 times. This good component performance can be attributed to Bphen's (1) deeper Unoccupied Molecular Orbital (LUMO) (-2.9 eV), which re-duces the energy barrier of electrons injection into the host CBP, making the carrier more balanced; (2) deeper Highest Occupied Molecular Orbital (HOMO) (-6.3 eV), which effectively block the holes in the emissive layer and increases the effective recombination zone; (3) higher electron mobility, which makes the electron transfer more efficient than TPBi at the same voltage, increases the generation of excitons probability in the emissive layer, and improves the performance of the devices.

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