化学学报 ›› 2025, Vol. 83 ›› Issue (1): 17-24.DOI: 10.6023/A24100310 上一篇    下一篇

研究论文

基于吩嗪受体单元的高效近红外热激活延迟荧光

马金珠a, 李阳a, 高珊a, 赵越b, 丁磊c,*(), 周东营a,*(), 樊健a,*()   

  1. a 苏州大学功能纳米与软物质研究院 江苏省碳基功能材料与器件重点实验室 苏州 215123
    b 南京大学配位化学研究所 配位化学国家重点实验室 南京 210023
    c 苏州科技大学化学与生命科学学院 苏州 215127
  • 投稿日期:2024-10-17 发布日期:2024-12-25
  • 基金资助:
    国家重点研发计划(2020YFA0714604); 国家自然科学基金(22005184); 国家自然科学基金(62375193); 江苏省国际科技合作/港澳台科技合作项目(BZ2023053)

High-efficiency Near Infrared Thermally Activated Delayed Fluorescence Based on Phenazine Acceptor

Jinzhu Maa, Yang Lia, Shan Gaoa, Yue Zhaob, Lei Dingc(), Dongying Zhoua(), Jian Fana()   

  1. a Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials, Soochow University, Suzhou 215123, China
    b State Key Laboratory of Coordination Chemistry, Institute of Coordination Chemistry, Nanjing University, Nanjing 210023, China
    c School of Chemistry and Life Sciences, Suzhou University of Science and Technology, Suzhou 215127, China
  • Received:2024-10-17 Published:2024-12-25
  • Contact: *E-mail: dinglei@usts.edu.cn; dyzhou@suda.edu.cn; jianfan@suda.edu.cn
  • Supported by:
    National Key R&D Program of China(2020YFA0714604); National Natural Science Foundation of China(22005184); National Natural Science Foundation of China(62375193); International Science and Technology Innovation Cooperation/Hong Kong, Macao and Taiwan Science and Technology Innovation Cooperation Project of Jiangsu Province(BZ2023053)

分别以二苯并吩嗪和二吡啶并吩嗪为受体单元, 三苯胺为给体单元, 设计并合成了两种给体-受体-给体(D-A-D)型红色热激活延迟荧光(TADF)材料即10,13-双(4-(二苯基氨基)苯基)二苯并[a,c]吩嗪-3,6-二腈(BzPz-TPA)和10,13-双(4-(二苯基氨基)苯基)联吡啶并[3,2-a:2',3'-c]吩嗪-11,12-二腈(PyPz-TPA). 将两个氰基基团分别引入到BzPz-TPA和PyPz-TPA的受体单元上, 增强受体单元的吸电子能力. 在分子骨架中嵌入强给体-强受体单元, 并且因为二者间的空间位阻效应, 使BzPz-TPA分子和PyPz-TPA分子均具有扭曲D-A分子构型, 从而使其产生小的单线态-三线态能级差(ΔEST). 另外, 分子内给体和受体单元之间的氢键作用, 可以调控D-A分子构型以及最高占据分子轨道(HOMO)和最低未占分子轨道(LUMO)之间的重叠程度. 在BzPz-TPA分子中, 供体和受体单元之间的二面角为44°, D-A之间存在扭曲构型, 从而实现了HOMO和LUMO的有效分离, HOMO主要位于供体单元TPA上, 而LUMO主要位于受体单元上; 在PyPz-TPA分子中, 供体和受体单元之间的二面角为52°, D-A扭曲构型有效地分离了HOMO和LUMO, HOMO主要位于供体单元TPA上, LUMO主要位于受体单元上. 由于BzPz-TPA和PyPz-TPA具有相同的供体单元, 因此它们具有相似的HOMO能级. 由于两个发光分子均具有强的刚性骨架和较小的ΔEST, 将BzPz-TPA分子掺杂在主体材料4,4'-二(9-咔唑)联苯(CBP)中, 该有机发光二极管(OLED)器件在638 nm发射时, 其最大外量子效率(EQE)达到7.4%; PyPz-TPA分子掺杂在主体材料CBP中, 其OLED器件在676 nm发射时, 其最大EQE达到了22.6%; 并且当其在电致发射波长为714 nm时该器件达到了16.58%的最大EQE, 实现近红外发光.

关键词: 热激活延迟荧光, 单线态-三线态能极差, 外量子效率, 热稳定性, 电致发光性能

Two donor-acceptor-donor (D-A-D) type red thermally activated delayed fluorescence (TADF) materials 10,13- bis(4-(diphenylamino)phenyl)dibenzo[a,c]phenazine-3,6-dicarbonitrile (BzPz-TPA) and 10,13-bis(4-(diphenylamino)phenyl)- dipyrido[3,2-a:2',3'-c]phenazine-11,12-dicarbonitrile (PyPz-TPA) were designed and synthesized with dibenzophenazine and dipyridobenzazine as acceptor units and triphenylamine as donor units respectively. Two cyano groups were introduced into BzPz-TPA and PyPz-TPA to enhance the electron-withdrawing capability of the acceptor unit. Strong donor and acceptor units were introduced into the molecular skeletons of BzPz-TPA and PyPz-TPA, and steric hindrance between D and A units led to a twisted D-A configuration, thus achieving relatively small singlet-triplet energy gaps (ΔEST). In addition, the intramolecular hydrogen bonding interaction between donor and acceptor units can modulate the D-A molecular configuration and the overlap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). In the BzPz-TPA molecule, the dihedral angle between the donor and acceptor units is 44°, and there is a twisted configuration between D-A, thereby achieving effective separation of HOMO and LUMO. HOMO is mainly located on the donor unit TPA, while LUMO is mainly located on the acceptor unit. In PyPz-TPA molecule, the dihedral angle between the donor and acceptor units is 52°, and the D-A twisted configuration effectively separates the HOMO and LUMO. The HOMO is mainly on the donor unit TPA, and the LUMO is mainly on the acceptor unit. Since BzPz-TPA and PyPz-TPA have the same donor unit, they have similar HOMO energy levels. Due to the rigid skeleton of two molecules and the smaller ΔEST, the BzPz-TPA is doped into the host material 4,4'-bis(9-carbazole)biphenyl (CBP) and resulted in the maximum external quantum efficiency (EQE) of 7.4% for the organic light-emitting diode (OLED) device emitting at 638 nm. When PyPz-TPA is doped into the host material CBP, the OLED device achieved the maximum EQE of 22.6% at 676 nm emission. Besides, the OLED of PyPz-TPA achieved the maximum EQE of 16.58% and near-infrared luminescence at an emission wavelength of 714 nm.

Key words: thermally activated delayed fluorescence, singlet-triplet energy gap, external quantum efficiency, thermal stability, electroluminescence performance