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Updated: Aug 30, 2026

Scale-up Chemical Synthesis of Thermally-activated Delayed Fluorescence Emitters Based on the Dibenzothiophene-S,S-Dioxide Core
Published on: October 24, 2017
Host-controlled switching between TADF and RTP in acridone-carboline donor-acceptor dyads
Komal Vasant Barhate1, Juhi Dutta2, Neeraj Agarwal1
1School of Chemical Sciences, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Kalina, Santacruz (E), Mumbai 400098, India.
Abstract:
Purely organic, metal-free emitters that combine thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) provide an attractive route to triplet harvesting without heavy-metal complexes. Here, we report two acridone-carboline donor-acceptor emitters, Acr-Me-Cb and Acr-Anisyl-Cb, that exhibit bluish-green emission centered at 422 nm and high photoluminescence quantum yields of up to 85% in toluene. A moderate singlet-triplet energy gap (ΔEST ≈ 0.3 eV) enables competing reverse intersystem crossing and triplet stabilization pathways, allowing delayed fluorescence and phosphorescence to be accessed within the same molecular framework. Host-dependent photophysical studies in CBP and PVA matrices reveal distinct relaxation channels: 10 wt% CBP-doped films show TADF at 300 K with delayed lifetimes of 67 and 136 μs for Acr-Me-Cb and Acr-Anisyl-Cb, respectively, whereas rigid PVA films promote RTP with an afterglow of ∼1 s under ambient conditions. These results establish acridone-carboline dyads as a host-responsive platform for switching between TADF and RTP in metal-free organic emitters.
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