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Updated: Jan 9, 2026
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Scale-up Chemical Synthesis of Thermally-activated Delayed Fluorescence Emitters Based on the Dibenzothiophene-S,S-Dioxide Core
Published on: October 24, 2017
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A Direct Arylation Approach toward Thermally Activated Delayed Fluorescence-Active Benzo[c][1,2,5]thiadiazole
Sonny Brebels1,2, Emma V Puttock3, Tom Cardeynaels1,2,4
1Institute for Materials Research (IMO-IMOMEC), Hasselt University, Martelarenlaan 42, Hasselt B-3500, Belgium.
ACS Applied Optical Materials
|December 4, 2025
Summary
A new isomeric emitter, 2TPA-iCNBT, shows enhanced thermally activated delayed fluorescence (TADF) properties. This near-infrared (NIR) emitter achieves higher quantum yields and faster kinetics, outperforming previous designs.
Area of Science:
- Organic Chemistry
- Materials Science
- Photophysics
Background:
- Near-infrared (NIR) emitters are crucial for advanced optoelectronic applications.
- Thermally activated delayed fluorescence (TADF) materials offer high efficiency in organic light-emitting diodes (OLEDs).
- Optimizing donor-acceptor (D-A) structures is key to enhancing TADF properties.
Purpose of the Study:
- To design and synthesize a novel isomeric emitter (2TPA-iCNBT) with improved NIR-TADF characteristics.
- To investigate the impact of D-A substitution patterns and donor group numbers on emitter performance.
- To explore a new direct arylation strategy for efficient synthesis of TADF emitters.
Main Methods:
- Synthesis of four novel emitters, including 2TPA-iCNBT, 2TPA-CNBT, 1TPA-CNBT, and 1TPA-iCNBT, using a direct arylation strategy.
- Characterization using spectroscopic techniques (steady-state and time-resolved emission spectroscopy).
- Computational modeling using Density Functional Theory (DFT) to simulate molecular geometry and excited states.
- Device fabrication and testing of solution-processed OLEDs to evaluate external quantum efficiency (EQE).
Main Results:
- 2TPA-iCNBT demonstrated significantly enhanced TADF properties, with a photoluminescence quantum yield increase from 27% to 55% in the absence of oxygen.
- Fastest TADF emission kinetics (k_RISC ~ 10^5 s^-1) were observed for 2TPA-iCNBT in doped films.
- 2TPA-iCNBT achieved a maximum EQE of 2.49% in OLEDs, outperforming the reference 2TPA-CNBT (1.16%) and maintaining high EQE at higher current densities (1.98% at 10 mA cm^-2).
Conclusions:
- The D-A substitution pattern and the number of donor groups critically influence NIR-TADF emitter performance.
- The designed isomeric emitter 2TPA-iCNBT exhibits superior TADF properties and device efficiency compared to the reference.
- The direct arylation strategy provides an efficient route for synthesizing functionalized TADF emitters.
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