雙鄰位結合的咪唑/雙芳香胺取代之雙苯基茀融合系統在有機電致發光材料的研究

林蓓羚

指導教授 ： 陳建添

國立臺灣師範大學/理學院/化學系/碩士(2007年)

摘要

我們開發出以苯環對位有二芳香胺取代的咪唑 ( Imidazole ) 為主體螢光材料，各別將苯環的鄰位連接到茀的C9位置形成旋環化合物Spiro-BI，此以推電子的三芳香胺片段與接收電子的咪唑片段做搭配，使得主體結構具有偶極 ( Dipolar ) 的特性，我們將這類化合物應用在有機發光二極體 ( OLED) 元件的研究，希望能在此材料層有效形成光激子 ( Exction )作為發光層。
本論文利用X-ray晶格繞射確立結構後，再以熱重分析儀評估其熱穩定性，發現這一系列化合物在熱穩定性上Td值的範圍可高達400oC以上。接著對此類化合物進行吸收、放射光譜、螢光量子產率的測量，同時也利用循環伏安法評估其氧化還原行為和推測其HOMO-LUMO能階。發現此系統化合物具有可逆的氧化峰且大約在5 eV左右，因此推測其適合作為電洞傳輸兼發光層。
我們以光物理與電化學性質為基礎，預期此類化合物適合作為電洞傳輸兼發光層。於是我們將其搭配合適的電子傳輸層和電洞阻檔層，來製作發光二極體元件，並測量其光電性質。發現化合物6a所構成的深藍光?層元件正如我們預期的展現出優良的元件效率，元件結構為ITO/6a/BCP/Alq3/LiF/Al時，驅動電壓只有3 eV，最大亮度達5688 cd/m2，在電流密度100 mA/cm2時，量子產率為2.47 ％，電流效率2.21 cd/A及功率0.96 lm/W，CIE座標為（0.15，0.10），放光最大波長值為436 nm，半高波寬只有56 nm。

關鍵字

有機發光二極體

並列摘要

We used 4,5-diphenyl-imidazole with diarylamino substituents at both para positions as a fluorescent template. Both ortho positions are linked to C9 positions of fluorine to form a spiro series of fluoene compounds spiro-BI. By taking advantage of the good electron accepting property of the central imidazole template and the efficient electron transporting (or hole-injection) property of the diarylamino appendages, we integrate them into such a fused, tri-cyclic spiro framework with a central 7-membered core ( Spiro-BI ).Because of the dipolar characteristics, these materials could form exciton effectively and serve as emitting layers in OLED divices. We plan to examine if the unique mode of molecular design is influential to the structural, optical, morphological, redox, and optoelectronic profiles of the resulting materials.
First of all, we identified the structure by X-ray crystrographic analysis. And also, in marked contrast to common donor-acceptor based materials, this new type of bipolar compounds displayed unique optical, morphological, redox and optoelectronic propensities. In conjunction with a suitable electron-transporting material-Alq3 and hole-blocking material-BCP, they served as potential deep-blue emitters in OLED devices. Preliminary optoelectronic studies of the Spiro-BI indicate that they act as good hole-transportor and emitters, reaching a maximum EL intensity of 5688 cd/m2. When the current density of the device was 100mA/cm2, its operational quantum yield is 2.5%. The operational luminance and power efficiency are 2.2cd/A and 1.0 lm/W, respectively. Particularly, the full-width at half maximum of the electroluminescence (?max 436 nm) in the device was only 56 nm. Its CIE coordinate was (0.15, 0.10), showing that it was a deep blue-light-emitting device. As far as a non-doped and non-phosphorescent deep-blue emitter was concerned, Spiro-BI revealed a competent device efficiency.

並列關鍵字

OLED

參考文獻

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