A Highly Twisted Carbazole‐Fused DABNA Derivative as an Orange‐Red TADF Emitter for OLEDs with Nearly 40 % EQE

Abstract

Multiple resonance (MR) type thermally activated delayed fluorescence (TADF) material is currently a research hotspot in organic light‐emitting diodes (OLEDs) due to their high color purity and high exciton utilization. However, there are only a handful of MR‐TADF emitters with emissions beyond the blue‐to‐green region. The very limited emission colors for MR‐TADF emitters are mainly caused by the fact that so far molecular modifications of MR‐TADF do not offer much change in the emission colors. Here, we report a new approach to modifying a prototypical MR core of DABNA by fusing carbazoles to the MR framework. The carbazole‐fused molecule (TCZ‐F‐DABNA) basically maintains the MR‐dominated features of DABNA while red‐shifting the emission. Its OLED achieves an external quantum efficiency of 39.2 % with a peak at 588 nm, which is a record‐high efficiency for OLEDs with peaks beyond 560 nm. This work provides a new approach for significantly tunning emission colors of MR‐TADF emitters.

Recent advances and prospects for organoboron-based thermally activated delayed fluorescence emitters

“…Its OLED achieved an EQE max of 39.2% at 588 nm and remained above 30.3% EQE even at high doping concentrations of 30 wt%. 130 In 2023, Yang et al proposed an effective method towards a long-wavelength MR-TADF emitter by integrating a strong electron-donating indolophenazine building block into the B/N-doped polycyclic aromatic hydrocarbons. The investigation of photophysical properties revealed that different electron-donating abilities had significant effects on luminescence features, including emission wavelength and FWHM.…”

“…Its OLED achieved an EQE max of 39.2% at 588 nm and remained above 30.3% EQE even at high doping concentrations of 30 wt%. 130…”

Isomerization design for improving the efficiency of red thermally activated delayed fluorescence emitters based on pyridopyrazinophenanthroline acceptor

“…[1][2][3][4][5] To date, TADF materials have been developed speedily, and the external quantum efficiency (EQE) of TADF devices have reached 40%. [6][7][8][9][10] However, these organic light-emitting diodes (OLEDs) devices with high EQE are mainly based on blue or green materials. In contrast, as one of the three primary colors indispensable in full-color displays, efficient red TADF-OLEDs still remain far behind.…”

Programming Positive Mechanofluorescence in Liquid Crystalline Elastomers

“…Carbazole is a recurrent and highly versatile scaffold within chemistry, biomedicine, and materials science because of its attractive luminescent and semiconductor properties, which can be fine-tuned through not only the subtle and rational modification of its molecular structure but also imparting control over the interactions established with the environment at the supramolecular level. − …”