Optimizing triazine-based thermally activated delayed fluorescence molecules for enhanced organic light-emitting...

Area of Science:

• Materials Science
• Organic Electronics
• Computational Chemistry

Background:

• Development of efficient organic light-emitting materials is crucial for advanced display and lighting technologies.
• Thermally activated delayed fluorescence (TADF) offers a pathway to achieve high internal quantum efficiencies in organic light-emitting diodes (OLEDs).
• Rational molecular design is key to tuning optoelectronic properties for specific applications.

Purpose of the Study:

• To design and computationally investigate novel cyanotriazine-based donor-π-acceptor emitters for TADF applications.
• To establish structure-property relationships governing TADF performance.
• To identify promising molecular designs for high-performance organic light-emitting materials.

Main Methods:

• Employed a rational design strategy for eleven cyanotriazine-based donor-π-acceptor molecules.
• Conducted comprehensive computational investigations using Density Functional Theory (DFT) and Time-Dependent DFT (TD-DFT).
• Evaluated geometric parameters, vertical excitation energies, singlet-triplet energy gaps (ΔE_ST), spin-orbit coupling matrix elements (SOCMEs), and reorganization energies.

Main Results:

• Identified eight promising candidates with ΔE_ST < 0.3 eV based on initial screening.
• TZCN-PXZ, TZCN-PTZ, and TZCN-ICbz demonstrated favorable combinations of small ΔE_ST and enhanced SOCME values, indicating efficient TADF.
• Moderately twisted conformations (≈70°) were found to balance ΔE_ST reduction and SOCME enhancement through LE-CT orbital mixing.

Conclusions:

• Established clear structure-property relationships for cyanotriazine-based TADF emitters.
• The designed molecules, particularly TZCN-PXZ, TZCN-PTZ, and TZCN-ICbz, show significant potential for efficient TADF applications.
• Provided valuable design guidelines for developing next-generation high-performance organic light-emitting materials.