|Abstract: ||本論文研究分為二個部分，第一部分研究二種雙極性主體材料，分別是將1,2,4-triazole連結在phenylcarbazole的對位以及間位上。並進一步測量分子間的關係、熱穩定性、電性特性以及光物理特性，再將其製備成元件並探討主體材料在有機磷光元件中的表現。當1,2,4-triazole連結在phenylcarbazole間位時的主體材料製作成元件擁有較高的效率，分別為8.8%, 16.7%, 17.5% 以及16.7%分別在藍光(FIrpic)、綠光[(ppy)2Ir(acac)]、黃光[(Bt)2Ir(acac)] 以及紅光[Os(bpftz)2(PPhMe2)2, OS1]，我們也以共蒸鍍單一發光層的方式將其製作成白光元件，效率可達到12.4%並擁有穩定的色彩表現。 另一部分我們研究由對稱分子組成的雙極性主體材料AC17與AC52，它們是由電洞傳輸的carbazole以及電子傳輸diphenyl phosphine oxide/oxadiazole所組成的。飽和的內部分子連接限制了其鍵共軛的有效延伸，導致相同的三重態能階 (ET = 2.97 – 2.98 eV) 。如此高的三重態能階以及雙極性的傳輸特性可以讓AC17與AC52在發光層中順利的將能量由主體轉移到客體材料並擁有平衡的載子傳輸性。因此，我們利用此泛用主體材料應用在各種磷光材料 (從藍光到紅光) ，顯示了相當平均的外部量子效率 (EQE= 8.2 – 13.1%) 以及較低的效率衰減。另外我們也利用分層蒸鍍發光層的方式來製作白光元件，其擁有良好的元件效率 (14.4%, 25.7 cd A‒1, 27 lm W‒1) 與當亮度由560燭光到15200燭光擁有高穩定的色彩表現 (CIEx = 0.26 – 0.28 and CIEy = 0.38) 。|
There are two topics of this thesis. One topic is to study two bipolar host materials, for which the phenylcarbazole and 1,2,4-triazole fragments are linked with either para- or meta-phenyl bridging unit. Furthermore, the relationship between their molecular structures and thermal, electrochemical and photophysical properties was addressed, and the inﬂuence of host materials on the performances of phosphorescent OLEDs have been studied. For all OLEDs, the higher efficiency was achieved for the m-cbtz based device with maximumEQE of 8.8%, 16.7%, 17.5% and 16.7% for blue (FIrpic), green [(ppy)2Ir(acac)], yellow [(Bt)2Ir(acac)], and red [Os(bpftz)2(PPhMe2)2, OS1], respectively. A two-emitter, all phosphorescent WOLED hosted by m-cbtz in single-emitting-layer gave a maximum EQEof 12.4% and with high chromatic stability. Another topic is to study chiral bipolar hosts AC17 and AC52 comprising HT carbazole and ET diphenyl phosphine oxide/oxadiazole with saturated linker. The saturated linker limited the effective extension of their-conjugation, leading to the same triplet energy (ET = 2.97 – 2.98 eV). Such high triplet energy and bipolar carrier transporting characteristics of AC17 and AC52 can facilitate the exothermic energy transfer to the dopants and the balanced carrier-injection/transporting in the emission layers (EMLs). As a result, they were utilized as universal hosts for various phosphorescent OLEDs (from blue to red), showing average external quantum efficiencies (EQE= 8.2 – 13.1%) and low efficiency roll-off. In addition, we also fabricated the dual-emitter WOLEDs with co-doped single emissive layer, exhibiting satisfactory device efficiencies (14.4%, 25.7 cd A‒1, 27 lm W‒1) and with highly stable chromaticity (CIEx = 0.26 – 0.28 and CIEy = 0.38) at brightness from 560 to 15200 nit.