Handbook of Aggregation-Induced Emission, Volume 3. Группа авторов

Handbook of Aggregation-Induced Emission, Volume 3 - Группа авторов


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      1.3.3 Hybridized Local and Charge Transfer Materials Aggregation‐induced Emissive Emitters

      Different from Kasha’s rule, “hot exciton” process can happen between higher, excited triplet states to emissive singlet TmSn (m ≥ 2), which was discovered in 1962 [123]. This process with 100% IQE in theory was often accompanied by HLCT excited state, where LE state decays fluorescently, while CT state upconverted from 3CT to 1CT and then to emissive 1LE state, as a result of close LE and CT states [28–31]. Ma et al. first reported several HLCT emitters of donor–acceptor (D–A) structures, and the related OLEDs’ excellent EL performance [28]. As the AIE characteristics also grafted into the HLCT materials, it enabled these emitters to have high efficiency in aggregated state, with spectrum from blue to green and red.

Schematic illustration of the structures of hybridized local and charge transfer materials aggregation-induced emissive emitters.

      Increasing the efficiency of OLED devices is a complex and integrated challenge in the long term. As for the EMLs, they might have multiple photophysical mechanisms coexisting in the emitters both at the molecular levels and in the aggregated state, therefore the strategic design for the emitters was highly required. Apart from the influence of emitters, many other factors also play significant roles in determining the efficiency of OLED devices such as processing methods, doping, and lighting‐extraction. When it comes to the application of emitters from the laboratory to commercial, these factors, including cost, stability, and lifetime of the device cannot be ignored. From these points, AIE emitters have already been applied in nondoped OLEDs with evident advantages of high efficiency, low cost, and high stability. In spite of these achievement, there is still enough room for developing AIE emitters in OLEDs, such as improving the efficiency of OLEDs or designing novel AIE emitters with other high EUE mechanism of triplet–triplet annihilation (TTA) [130, 131], triplet exciton‐polaron annihilation (TPA) [33], or singlet fission [132]. Finally, we hope that OLED devices will profit more from AIE emitters both academically and commercially in the future.

      This work is financially supported by the National Key R&D Program of China (2016YFB0401000, 2017YFE0106000), National Natural Science Foundation of China (21805296, 21876158, 51773212, 21574144 and 21674123), Zhejiang Provincial Natural Science Foundation of China (LR16b040002), Natural Science Foundation of Ningbo City (2018A610134), Ningbo Municipal Science and Technology Innovative Research Team (2015B11002 and 2016b10005), CAS Key Project of Frontier Science Research (QYZDB‐SSW‐SYS030), CAS Key Project of International Cooperation (174433KYSB20160065), and Zhejiang Provincial Natural Science Foundation of China (Grant No. LY20B040002).

      1 1 Tang, C. W., VanSlyke, S. A. Organic electroluminescent diodes. Appl. Phys. Lett. 1987; 51(12):913–5.

      2 2 Jeong, H., Shin, H., Lee, J., Kim, B., Park, Y. I., Yook, K. S., et al. Recent progress in the use of fluorescent and phosphorescent organic compounds for organic light‐emitting diode lighting. J. Photon. Energy. 2015; 5:23.

      3 3 Wei, Q., Fei, N., Islam, A., Lei, T., Hong, L., Peng, R., et al. Small‐molecule emitters with high quantum efficiency: mechanisms, structures, and applications in OLED devices. Adv. Opt. Mater. 2018; 6(20):1800512.

      4 4 Zou, S. J., Shen, Y., Xie, F. M., Chen,


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