市面上所販售的照明光源普遍含有過多藍光，已有眾多研究證實，入夜曝照藍光除了對眼睛及身體造成不可逆的傷害外，亦會造成生態的破壞及夜空的汙染，因此，一個無藍害的照明光源是市場上所歡迎的；燭光有機發光二極體（OLED），其所放出的光色有如蠟燭一般，又不會有使用蠟燭所帶來的缺點，為目前入夜使用人工照明的首選，可有效避免入夜後曝照藍光所帶來的傷害；然而作為照明使用，長壽命是很重要的一件事，而這正是OLED必需解決的一個重要議題，尤其是對以濕式製程製作之OLED，提升元件的壽命更是刻不容緩；因此，本研究以濕式製程製作一長壽命類燭光OLED，所製成之濕式OLED元件，為夜晚照明提供一低成本、高壽命的新選擇。
本研究使用4,4',4"-Tris(carbazol-9-yl)triphenylamine （TCTA）作為主體材料，並摻雜10 wt%橘紅光客體Tris(2-phenylquinoline)iridium(III) （Ir(2-phq)3）與10 wt%綠光共主體Tris[2-phenylpyridinato-C2,N]iridium(III) （Ir(ppy)3），以濕式製程研製出一長壽命燭光OLED，其能量效率(PE)可達30.5 lm/W，外部量子效率(EQE)達13.2 %，色溫為1,771 K，壽命（t50）在初始亮度1,000 cd/m2下可達87小時；元件的長壽命可歸因於：(1) 主體材料TCTA相能有效地將能量轉移給共主體與客體；(2) 主體材料TCTA有高的玻璃轉換溫度（Glass transition temperature, Tg），在熱蒸鍍過程中，可以形成表面平整的薄膜，且對元件長時間運作所產生的熱能有較高的耐受性，進而延長元件壽命；(3) 添加的綠光客體Ir(ppy)3可作為共主體的存在，將能量有效的轉移給Ir(2-phq)3橘紅光客體，達到更有效的能量利用與更少的能量損失，因而提升壽命。(4) 透過濃度的最佳化避免了濃度淬熄的發生，進而提升了元件的壽命。

Most emission of the commercial lighting sources contain too much blue light. Many research have found that exposure blue light at night may not only cause irreversible damages to human eyes and body but also lead to ecological damage and pollution of the night sky. Hence, a blue-hazard lighting source is welcomed in the market. Candlelight organic light-emitting diodes (OLED), which emits similar light color to that of a candle, without the disadvantages of candles, are currently the first choice for artificial lighting at night to effectively avoid the damage caused by exposure to blue light at night. However, for lighting purposes, long lifetime is a very important issue for OLED devices to solve. Especially for solution processed OLED, it is imperative to improve the lifetime of the device. Therefore, we carried out a solution processed long lifetime candlelight OLED. The produced solution processed OLED device provides a new chose of a low-cost, long-lifetime lighting source for in night lighting.
In this study, 4,4',4"-Tris(carbazol-9-yl)triphenylamine (TCTA) was used as the host material, doped with 10 wt% of Tris(2-phenylquinoline)iridium(III) (Ir(2-phq)3) as an orange-red dopant and 10 wt% of Tris[2-phenylpyridinato-C2,N]iridium(III) (Ir(ppy)3) as green light co-hosted to developed a long lifetime solution processed candlelight OLED. Which shows an power efficacy (PE) of 30.5 lm/W, an external quantum efficiency (EQE) of 13.2%, and the color temperature of the device is 1,771 K with a lifetime (t50) of 67.8 hours under the initial brightness of 1,000 cd/m2. The long lifetime of the component can be attributed to: (1) Host material TCTA can effectively transfer energy to the co-host and guest. (2) Host material TCTA has a high glass transition temperature (Tg) which can form a flat film during the thermal evaporation process. And this property can lead to a higher tolerance to the thermal energy generated while long-term operation of the device, thereby prolong the lifetime of the device. (3) The added of the green dopant Ir(ppy)3 can exist as a co-host, which can effectively transfers energy to the orange-red dopant Ir(2 -phq)3 to achieve a more effective energy utilization and less energy loss, thus increase the lifetime. (4) Through the optimization of the doping concentration, the occurrence of concentration quenching is avoided, hence improved the lifetime of the device.

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