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.

Automated summary

Two new anthracene-based emitters, pipdAnCz and pipdAnTPA, are designed and synthesized to improve the efficiency of organic light-emitting diodes (OLEDs) by converting triplet excitons to singlet excitons. Both emitters possess characteristics of hot exciton and triplet-triplet annihilation (TTA), enabling the conversion of triplet excitons to singlet excitons from different energy levels.