Competitive Relaxation Pathways of Dibenzophenanthroline Isomer Emission: Charge-Transfer, Excimer Formation

Area of Science:

• Photophysics and excited-state dynamics
• Materials science of nonlinear heteroacenes
• Organic electronics

Background:

• Nonlinear heteroacenes possess unique photophysical properties.
• Understanding excited-state dynamics is crucial for material design.
• DBP6 (bis-phenylethynyl-substituted dibenzophenanthroline) is a promising derivative.

Purpose of the Study:

• To systematically investigate the photophysical properties and excited-state dynamics of DBP6.
• To elucidate the competitive relaxation pathways governing its dual-emission behavior.
• To explore the potential applications of DBP6 in optoelectronics.

Main Methods:

• Steady-state spectroscopy
• Time-resolved fluorescence measurements
• Density functional theory (DFT) calculations
• Solvent polarity-dependent studies

Main Results:

• DBP6 exhibits dual emission governed by charge-transfer (CT) and intramolecular benzene excimer formation.
• Excitation wavelength and solvent polarity significantly influence emission wavelengths and lifetimes.
• DFT calculations corroborate experimental findings, predicting S1 emission at 495 nm.
• Stable π-π interactions between phenyl rings contribute to excimer emission.

Conclusions:

• DBP6 displays tunable dual emission, controllable via excitation and solvent polarity.
• The study advances the understanding of excited-state interactions in nonlinear heteroacenes.
• DBP6 shows potential for ratiometric sensing, organic light-emitting diodes (OLEDs), and energy conversion systems.