Triplet-triplet upconversion (TTU), where two low-energy triplet excitons are converted to one higher energy singlet exciton, is excellent approach to break through the theoretical limit of the pure fluorescent organic light-emitting diodes (OLEDs) by 5%. To data, however, the reported emitters with high emission efficiency and efficiently TTU in film state are rare. Herein, we design the blue aggregation-induced emission luminogens (AIEgens) and investigate their upconversion efficiency. TPA-An-mPhCz can not only achieve high emission efficiency in the film state, but also show high upconversion efficiency of close to 50% even though the calculated energy level of the triplet excitons (T2) is lower than 2T1. A possible upconversion mechanism is proposed according to the transient electroluminescence spectra and theoretical calculation. This strategy may provide a new platform for the construction of highly efficient non-doped blue OLEDs based on TTU and AIEgens.

中文翻译：

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基于高效三重三重上转换和聚集诱导发射的高性能非掺杂蓝色OLED

三重态三重态上转换（TTU）将两个低能三重态激子转换为一个高能单重态激子，是突破纯荧光有机发光二极管（OLED）理论极限5％的极佳方法。对于数据，然而，报道的具有高发射效率和有效的薄膜状态下的TTU的发射器很少。在本文中，我们设计了蓝色聚集诱导的发射发光剂（AIEgens），并研究了它们的上转换效率。TPA-An-mPhCz不仅可以在薄膜状态下实现高发射效率，而且即使三重态激子（T2）的计算能级低于2T1，也可以显示接近50％的高上转换效率。根据瞬态电致发光光谱和理论计算，提出了一种可能的上转换机理。