Anthracene derivatives with hot exciton and TTA process for high-efficiency organic light-emitting diodes

Organic fluorophores with unique photophysical properties that converting the triplet excitons to singlet exci-tons, are desired to improve the efficiencies of organic light-emitting diodes (OLEDs). Here, two new anthracene-based emitters pipdAnCz and pipdAnTPA, with proper donor and acceptor substituents are designed and syn-thesized. The theoretical calculation and experimental results demonstrate that both pipdAnCz and pipdAnTPA possess hot exciton and triplet-triplet annihilation (TTA) characteristics, which can convert the triplet excitons to singlet excitons from the high-lying triplet energy levels (Tn) and the lowest triplet energy level (T1) respectively. Due to its relative higher photoluminescence quantum yields (PLQYs), the pipdAnTPA based non-doped device achieved a maximum external quantum efficiency (EQEmax) of 6.43% with an exciton utilization efficiency (EUE) of 72%. Further device physics study reveal that the hot exciton process is the dominant mechanism, assisted by TTA process, to convert the triplet excitons, especially for the pipdAnTPA based device.