期刊
ADVANCED MATERIALS
卷 33, 期 11, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adma.202006953
关键词
aggregation‐ induced emission; deep‐ blue organic light‐ emitting diodes; high‐ lying triplet excitons; magnetic field effect
类别
资金
- National Natural Science Foundation of China [21788102, 51527804, 91833304, 61975057, 11661131001]
- Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, China [2019B030301003]
- Guangzhou Science & Technology plan project [201804010456]
The research focuses on improving the efficiency of triplet excitons in AIE materials through spin conversion process. The relative positions of T-n and S-1 were found to significantly affect the efficiency, leading to the development of a highly efficient deep-blue fluorescent OLED.
Aggregation-induced emission (AIE) materials are attractive for achieving highly efficient nondoped organic light-emitting diodes (OLEDs) owing to their strong luminescence in the solid state. However, the electroluminescence efficiency of most AIE-based OLEDs remains low owing to the waste of triplet excitons. Here, using theoretical calculations, photophysical dynamics, and magnetoluminescence measurements, the spin conversion process is demonstrated between the high-lying triplet state (T-n) and the lowest excited singlet state (S-1) in AIE materials. Moreover, the relative positions of T-n (n < 4) and S-1 are shown to have a significant impact on the spin-conversion efficiency, thus influencing the harvesting of triplet excitons and the device efficiency. Finally, by selecting an upconversion material with an appropriate energy level for further utilizing the triplet excitons, a deep-blue fluorescent OLED with CIE coordinates of (0.15, 0.08), a maximum external quantum efficiency of 10.2%, low efficiency roll-off, and a high brightness of 16817 cd m(-2) is developed. This is one of the most efficient deep-blue OLEDs based on AIE materials reported so far. These findings also provide new insights into the design of more efficient AIE molecules and corresponding OLEDs by managing high-lying triplet excitons.
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