Related Experiment Video
Updated: Jan 8, 2026

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light
Published on: September 12, 2014
Modulating the Singlet-Triplet Energy Gap With Regio-Specific Substitution on Dibenzo[a,c]phenazine to Realize Red
Komal Vasant Barhate1, Smruti Ranjan Nayak1, Mohammad Amir Ahemad2
1School of Chemical Sciences, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai, India.
Abstract:
Developing efficient orange-red emitters based on donor-acceptor (D-A) π conjugates with thermally activated delayed fluorescence (TADF) remains a significant challenge. Herein, we designed a series of donor-acceptor emitters (3,6-Az-DBP, 2,7-Az-DBP, and 2-Az-DBP) by incorporating twisted 10,11-dihydro-5H-dibenzo[b,f]azepine (Az) as a donor alongside the rigid and planar dibenzo[a,c]phenazine (DBP) acceptor core molecule at different sites viz., 3,6-, 2,7-, and 2- positions. As a result of site-specific substitution, considerable alteration in electronic properties was observed. For 3,6-Az-DBP, the energy gap between singlet and triplet states (ΔEST) was found to be 0.42 eV, which is much higher than that for 2-Az-DBP (0.25 eV) and 2,7-Az-DBP (0.06 eV). Owing to miniscule ΔEST, 2-Az-DBP and 2,7-Az-DBP showed orange and red TADF, respectively, in CBP blend. Both these compounds also showed red room temperature phosphorescence in powder samples having lifetimes in milliseconds time regime. Further, organic light emitting diode (OLED) of CBP doped 2-Az-DBP showed a high luminance of 6 × 103 Cd/m2 @ current density of 50 mA/cm2with EQEmax of about 12.3%. These studies provide a promising strategy, site selective substitution of donor on acceptor core, to improve the emission properties for red TADF emitters.
More Related Videos
Related Concept Videos
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Deactivation Processes: Jablonski Diagram
Woodward–Hoffmann Selection Rules and Microscopic Reversibility

