Li Wan, Chasing Pongsakorn, Nalaoh Phattananawee, Chawanpunyawat Thanyarat, Sukpattanacharoen Chattarika, Kungwan Nawee, Sudyoadsuk Taweesak, Promarak Vinich
Department of Materials Science and Engineering, School of Molecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, 21210, Wangchan, Rayong, Thailand.
Department of Chemistry, Faculty of Science, Chiang Mai University, Muang District, 50200, Chiang Mai, Thailand.
Chem Asian J. 2022 Jul 15;17(14):e202200266. doi: 10.1002/asia.202200266. Epub 2022 May 24.
Herein, three hydroxy-tetraphenylimidazole (HPI)-based fluorophores (HPI-TPA, HPI-PCz, and HPI-CzP) are designed and synthesized by disubstituted HPI core with arylamine units of triphenylamine (TPA), phenyl carbazole (PCz), and carbazole phenyl (CzP) at 3,5-positions of the N-phenyl ring of HPI, respectively. Their photophysical properties are theoretically and experimentally examined. HPI-TPA shows a hybridized local and charge transfer (HLCT) excited state characteristic and emits deep blue color via an HLCT mechanism, while both HPI-PCz and HPI-CzP exhibit excited-state intramolecular proton transfer (ESIPT) property and display pure keto form emissions. They possess high thermal stability and are successfully fabricated as emitters in organic light-emitting diodes (OLEDs). All devices exhibit intense blue color emissions with low turn-on voltages (3.5-3.7 V). Particularly, HPI-TPA-based OLED emits light in the deep-blue region with a high maximum external quantum efficiency (EQE ) of 3.77% and a decent efficiency roll-off.
在此，通过在羟基四苯基咪唑（HPI）的N-苯基环的3,5位分别用三苯胺（TPA）、苯基咔唑（PCz）和咔唑苯基（CzP）的芳胺单元对HPI核心进行二取代，设计并合成了三种基于HPI的荧光团（HPI-TPA、HPI-PCz和HPI-CzP）。对它们的光物理性质进行了理论和实验研究。HPI-TPA表现出杂化局域和电荷转移（HLCT）激发态特征，并通过HLCT机制发射深蓝色光，而HPI-PCz和HPI-CzP都表现出激发态分子内质子转移（ESIPT）性质，并显示纯酮形式发射。它们具有高的热稳定性，并成功地制备成有机发光二极管（OLED）中的发光体。所有器件都表现出强烈的蓝色发射，开启电压低（3.5 - 3.7 V）。特别地，基于HPI-TPA的OLED在深蓝色区域发光，具有3.77%的高最大外量子效率（EQE）和良好的效率滚降。
