Designing thermally activated delayed fluorescence emitters with through-space charge transfer: a theoretical study.

Area of Science:

• Materials Science
• Organic Electronics
• Computational Chemistry

Background:

• Thermally activated delayed fluorescence (TADF) molecules with through-space charge transfer (TSCT) are crucial for high-efficiency organic light-emitting diodes (OLEDs).
• Molecular structure significantly impacts the performance of TSCT-TADF materials.
• Theoretical investigations are vital for designing novel, high-performance TSCT-TADF molecules.

Purpose of the Study:

• To theoretically investigate the photophysical properties of two reported TSCT-TADF molecules (AC-BO and QAC-BO).
• To establish structure-property relationships for TSCT-TADF molecules.
• To design novel TSCT-TADF molecules with enhanced properties, specifically deep-blue emission and high efficiency.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Analysis of excited state energy levels and photophysical properties.
• Structure-property relationship analysis to guide molecular design.

Main Results:

• Calculated photophysical properties for AC-BO and QAC-BO align well with experimental data.
• Three novel TSCT-TADF molecules (DQAC-DBO, DQAC-SBO, DQAC-NBO) were designed.
• Designed molecules exhibit deep-blue emission and high reverse intersystem crossing rates (kRISC).

Conclusions:

• A nearly coplanar orientation of donor and acceptor units is critical for achieving high kRISC and fluorescence efficiency in TSCT-TADF molecules.
• The study provides insights into designing efficient deep-blue emitting TSCT-TADF materials.
• Theoretical calculations serve as a powerful tool for rational molecular design in organic electronics.