以[2.2]對環芳建構的雙極性有機發光二極體材料

Abstract

本研究合成出六個以PCP（[2.2]paracyclophane）為結構核心的HJJ系列雙極性分子，藉由引入不同的推電子基（arylamine或 9H-carbazole），搭配cyano拉電子基，以及共軛鏈長之改變來調控分子雲的定域化程度，五個分子結構且經過X-ray晶體繞射圖譜鑑定。此系列分子擁有寬能隙(> 3.25 eV)，螢光光色在極性溶劑和非極性溶劑中皆屬紫／藍光。此系列分子的熱裂解溫度在250 oC以上。HJJ-2發現薄膜態有堆疊誘導強化發光現象，其螢光量子產率高達82%，且具有雙極性載子傳輸能力。以之作為發光層製成電激發光元件，外部量子效率可達約0.5%。以上化合物具有做為藍光發光材料或摻雜發光材料之主體（host）材料的潛力。Six [2.2]paracyclophane derivatives, HJJ, have been synthesized. The electronic cloud localization of the molecules is tuned by varying electron donor (diphenylamine or 9H-carbazole) and electron acceptor (cyano) at the pseudopara sites of the [2.2]paracyclophane, and the conjugation length. Among them, five compounds were structurally characterized by single crystal X-ray diffraction. The six new compounds have a large HOMO/LUMO gap (> 3.25 eV) and emit purple/blue light. The thermal decomposition temperatures of the compounds are higher than 248 oC. In the film state, compound HJJ-2 exhibits aggregation-induced emission enhancement behavior with a high film quantum yield of 82%. Moreover, it exhibits bipolar carrier transport characteristics, and its electron and hole mobilities are 1.47 × 10-3 and 1.15×10-6 cm2/Vs, respectively. OLED device using the compound as the emitting layer has an external quantum efficiency (EQE) of 0.5%. The new compounds are potential blue light emitters or hosts for emitting fluorophores.