咔唑或三咔唑與苯并咪唑環化之菲啶化合物雙極材料之合成、性質探討以及在磷光有機發光二極體之應用

Synthesis and Characterization of Carbazole or Tricarbazole Substituted Benzimidazo<1,2-f>phenanthridine Bipolar Materials and their Aplications in PhOLED

陳雨欣(Yu-Hsin Chen)

指導教授 ： 梁文傑

國立臺灣大學/理學院/化學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201901649

摘要

本篇論文利用咔唑 (Carbazole) 及三咔唑 (Tricarbazole，3cbz) 修飾在苯并咪唑環化之菲啶化合物 (Benzimidazo<1,2-f>phenanthridine，CBIZ) 的10號碳、8號碳和6號碳上，合成了五個雙偶極 (Bipolar) 化合物。根據過往之研究報導，咔唑及三咔唑具有高三重態能階及良好的電洞傳輸特性，而苯并咪唑 (Benzimidazole) 具備良好的電子傳輸特性。本研究藉由一個碳-碳鍵的形成，將苯并咪唑改良為苯并咪唑環化之菲啶化合物，期許能在不增加分子量的條件下，增加結構的剛性以提升分子的熱穩定性。此外，亦期望此共平面結構能提升材料的電子傳輸效率，使整體分子的電洞傳輸效率和電子傳輸效率更平衡，進而提升有機發光二極體元件的表現。
在分子設計上，咔唑及三咔唑以碳-氮鍵且正交鍵結 (Orthogonally linkage) 之方式修飾在苯并咪唑環化之菲啶化合物，以維持分子的高三重態能階。本研究針對化合物之熱性質、光物理性質和電化學性質進行分析，結果顯示此五個化合物均具有高玻璃轉換溫度和出色的三重態能階。此外，亦透過X-Ray單晶繞射進行晶體結構排列的研究與探討。
以本研究所合成之化合物應用於磷光有機發光二極體元件的製作。其中，本研究所合成之化合物4-cbzCBIZ與化合物ID5皆摻混FIrpic，形成一有效之雙發光層元件。元件測量結果顯示，電荷密度20 mA/cm2的驅動電壓為7.84 V、最大亮度為15540 cd/m2、最大電流效率為20.02 cd/A、最大外部量子產率為8.83 %，以及生命期達到221分鐘。

關鍵字

咔唑 ； 三咔唑 ； 苯并咪唑環化之菲啶化合物 ； 雙偶極 ； 磷光有機發光二極體

並列摘要

In this thesis, five bipolar compounds based on carbazole or tricarbazole substituted benzimidazo<1,2-f>phenanthridine have been synthesized which the carbazole as well as tricarbazole are C10, C8 and C6-linked to the benzimidazo<1,2-f>phenanthridine unit. According to previous reports, carbazole and tricarbazole are renowned hole-transporting moieties, and benzimidazole plays an important role in electron-transporting materials. However, looking forward to enhancing electron mobility and securing higher thermal properties, we transform benzimidazole unit to benzimidazo<1,2-f>phenanthridine unit by connecting one bond.
In order to synthesize molecules with high triplet state, units are expected to be orthogonally linked with each other to twist the conformation. In addition, the thermal properties, photophysical properties, and electrochemical properties have been carefully evaluated, and the results show that all of these compounds possess not only a high glass transition temperature but a high triplet energy state as well. The crystal arrangement of these compounds has been studied through X-Ray single crystal diffraction.
One of our novel host material 4-cbzCBIZ along with compound ID5 forms an effective FIrpic-doped double-emitting layer. The corresponding blue PhOLED device shows excellent performance with the turn-on voltage of 7.84 V at 20 mA/cm2, a maximum luminance of 15540 cd/m2, a maximum current efficiency of 20.02 cd/A, a maximum external quantum efficiency of 8.83%, and a maximum lifetime of 221 minutes.

並列關鍵字

carbazole ； tricarbazole ； Benzimidazo<1,2-f>phenanthridine ； bipolar ； PhOLEDs

參考文獻

1. 陳金鑫; 黃孝文, OLED 有機電致發光材料與器件. 2007.

2. Bernanose, A., Electroluminescence of organic compounds. Br. J. Appl. Phys. 1955, 6 (S4), S54-S55.

3. Pope, M.; Kallmann, H. P.; Magnante, P., Electroluminescence in Organic Crystals. J. Chem. Phys. 1963, 38 (8), 2042-2043.

4. Tang, C. W.; VanSlyke, S. A.; Chen, C. H., Electroluminescence of doped organic thin films. J. Appl. Phys. 1989, 65 (9), 3610-3616.

5. Burroughes, J. H.; Bradley, D. D. C.; Brown, A. R.; Marks, R. N.; Mackay, K.; Friend, R. H.; Burns, P. L.; Holmes, A. B., Light-emitting diodes based on conjugated polymers. Nature 1990, 347 (6293), 539-541.