化学学报 ›› 2020, Vol. 78 ›› Issue (7): 680-687.DOI: 10.6023/A20030097 上一篇    下一篇

研究论文

氰基取代的螺芴氧杂蒽衍生物:激基复合物发光与性质调控

曹洪涛a, 李波a, 万俊a, 余涛a, 解令海a, 孙辰b, 刘玉玉a, 王锦a, 黄维a,c   

  1. a 南京邮电大学信息材料与纳米技术研究院 有机电子与信息显示国家重点实验室培育基地 南京 210023;
    b 西班牙马德里高等研究中心纳米研究所 马德里 28049;
    c 西北工业大学柔性电子前沿科学中心 西安 710072
  • 投稿日期:2020-03-31 发布日期:2020-06-04
  • 通讯作者: 解令海, 刘玉玉, 黄维 E-mail:iamlhxie@njupt.edu.cn;iamyyliu@njupt.edu.cn;iamwhuang@njupt.edu.cn
  • 基金资助:
    项目受国家自然科学基金(Nos.61605090,61604081,61604076,21774061,91833306)、江苏省自然科学基金(BK20190090,BK20180751)、江苏省“六大人才高峰”创新人才团队项目(XCL-CXTD-009)和江苏省高校优势学科建设工程(YX030003)资助.

Cyano-substituted Spiro[fluorine-9,9'-xanthene] Derivatives: Exciplex Emission and Property Manipulation

Cao Hongtaoa, Li Boa, Wan Juna, Yu Taoa, Xie Linghaia, Sun Chenb, Liu Yuyua, Wang Jina, Huang Weia,c   

  1. a Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications (NUPT), Nanjing 210023, China;
    b Madrid Institute for Advanced Studies in Nanoscience, IMDEA Nanociencia Calle Faraday 9, Ciudad Universitaria de Cantoblanco 28049, Spain;
    c Frontiers Science Center for Flexible Electronics (FSCFE), Shaanxi Institute of Flexible Electronics (SIFE) & Shaanxi Institute of Biomedical Materials and Engineering (SIBME), Northwestern Polytechnical University (NPU), Xi'an 710072, China
  • Received:2020-03-31 Published:2020-06-04
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Nos. 61605090, 61604081, 61604076, 21774061, 91833306), the Natural Science Foundation of Jiangsu Province (BK20190090, BK20180751), the Six Peak Talents Foundation of Jiangsu Province (XCL-CXTD-009) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD, YX030003).

热活化延迟荧光分子因具有高效发光、价格低廉等优点,在发展有机发光二极管方面显示出巨大潜力.与单分子相比,激基复合物容易实现小的单线态-三线态能隙差,在开发延迟荧光材料方面备受关注.然而,相应受体材料的种类仍较为稀少,且激基复合物延迟荧光性质与受体材料结构之间的关系还需深入探讨.本工作设计合成出两个新型的基于螺芴氧杂蒽的电子受体材料(CNSFDBX和DCNSFDBX).结果表明,它们与给体材料TCTA掺杂后均呈现激基复合物发射,其中TCTA:DCNSFDBX掺杂体系显示更高的发光效率,其原因归结为双氰基取代使得DCNSFDBX具有更强的接收电子的能力.该工作为开发新型电子受体材料用于激基复合物延迟荧光提供了思路.

关键词: 螺芴氧杂蒽, 激基复合物发光, 热活化延迟荧光, 空间位阻, 氰基取代

Thermally activated delayed fluorescence (TADF) molecules have great potential in developing organic light-emitting diodes (OLEDs) because of their efficient emission and low price. Compared to pure-molecules, exciplex systems are drawing much attention since they can realize small singlet-triplet energy splitting (ΔEST) more easily for TADF. However, the species and molecular design systems of electron-acceptors for exciplex-TADF are still limited even though some acceptors have been reported. In addition, the relationship between TADF properties and the structures of acceptors requires further investigations. Herein, we report the design and synthesis of two novel spiro[fluorine-9,9'-xanthene]-based acceptors (CNSFDBX and DCNSFDBX) for achieving exciplex-emissions by using tris(4-carbazoyl-9-ylphenyl)amine (TCTA) as a donor. The photoluminescence measurements suggest that both of the doping-systems (TCTA:CNSFDBX and TCTA:DCNSFDBX) possess exciplex emissions. Whereas, it is observed that the TCTA:DCNSFDBX system displays higher photoluminescence quantum yield and electroluminescence efficiency than TCTA:CNSFDBX. For better explaining this phenomenon, we perform low-temperature fluorescence and phosphorescence spectra investigations. The experimental results show that the TCTA:DCNSFDBX system exhibits smaller ΔEST values (0.12 eV) than TCTA:CNSFDBX (0.46 eV). This results indicate that the reverse intersystem crossing from non-radiative triplet states (T1) to radiative singlet states (S1) and TADF processes can be realized more easily in the TCTA:DCNSFDBX system. Moreover, the electrochemical measurements and theoretical calculations suggest that the lowest unoccupied molecular orbital (LUMO) level of DCNSFDBX (-2.86 eV) is lower than that of CNSFDBX (-2.47 eV). This situation implies that DCNSFDBX possesses stronger electron-accepting ability than CNSFDBX with the help of dicyano-substitution. Furthermore, the TCTA:DCNSFDBX system displays larger driving force (0.39 eV) than TCTA:CNSFDBX (0.22 eV) in their exciplex-formation processes, suggesting the exciplex-emission (TCTA:DCNSFDBX) can be achieved more easily. Therefore, the higher exciplex-emission efficiencies of the TCTA:DCNSFDBX system are attributed to the stronger electron-acceptability of DCNSFDBX through dicyano- substitution and larger driving force in its exciplex emission process. This work provides a route to further development of new electron-acceptors for exciplex-TADF.

Key words: spiro[fluorine-9,9'-xanthene], exciplex emission, thermally activated delayed fluorescence, steric hindrance, cyano-substitution