Title
Effect of increasing electron donor units for high-efficiency blue thermally activated delayed fluorescence
Author
Jae-Ryung Cha, Chil-Won Lee, Myoung-Seon Gong
Year
2017
Journal
Dyes and Pigments
Abstract
To enhance the efficiency of organic light-emitting diodes (OLEDs), the application of triplet excitons must be maximized. Two donor–acceptor-type molecules bearing bis-carbazolyl and tris-carbazolyl groups at the ortho position of a phenyl-attached triazine ring were synthesized. These molecules showed very small singlet–triplet energy gaps (ΔEST) of 0.06 and 0.03 eV, respectively, and transient photoluminescence (PL) characteristics, which indicate that they are thermally activated delayed fluorescence (TADF) materials. A high external quantum efficiency (EQE) of 16.5% with deep blue color coordinates of (0.15, 0.22) was observed using a TrisCz–Trz TADF emitter. This interaction between the electron donor and electron acceptor substituents plays a key role in achieving a very small ΔEST and good intramolecular charge transfer (ICT) activities with high photoluminescence (PL).
Instrument
FP-6500
Keywords
Fluorescence, Photoluminescence, Materials, LEDs