Development of Blue Emitting Materials for Thermally Activated Delayed Fluorescent Organic Light-Emitting Diodes using An Auxiliary Acceptor

摘要

We synthesized two blue thermally activated delayed fluorescence (TADF) emitters, TAZtCz-1 and TAZtCz-2 based on a molecular design concept introducing auxiliary acceptor. These two emitters are designed to control acceptor strength of triazine moiety by introducing another accepting unit for controlled emitting wavelength. The t-butyl substituted carbazole moiety was used as a donor. Their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were -6.10/-3.49 and -6.07/-3.33 eV and the singlet and triplet energy were 2.86/2.70 and 2.92/2.74 eV. The two emitters showed small singlet and triplet energy gap (ΔE_(ST)) below 0.2 eV. Maximum external quantum efficiency of two emitters showed above 20% and the color coordinate of (0.21, 0.42) and (0.15, 0.17).