Interexcited State Photophysics II: A Qualitative Excited State Dynamics Model from First-Principles

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Photophysics

Background:

• Previous work established reliable DFT methods for S1 to S0 internal conversion in perylene.
• Excited state dynamics in perylene, particularly intersystem crossing, require accurate theoretical modeling.

Purpose of the Study:

• To calculate excited state dynamics in perylene using validated DFT methods.
• To investigate the accuracy of DFT for predicting interexcited state internal conversion rates.
• To refine DFT methodology for improved photophysical predictions.

Main Methods:

• Utilized five validated density functional and basis set combinations from Part I.
• Employed density functional theory (DFT) to model excited state dynamics up to the second excited state.
• Applied a faux-damping function to correct overestimated nuclear-electronic couplings.

Main Results:

• DFT initially overestimated interexcited state internal conversion (IC) rates by up to 10 orders of magnitude.
• A faux-damping correction significantly reduced calculated IC rates, yielding good agreement with experimental values for S2 to S1.
• The PBE0/def2-TZVP method provided accurate predictions for photoluminescence quantum yields (PLQY) and anti-Kasha quantum yields (AKQY).

Conclusions:

• Validated DFT methods, with a faux-damping correction, can qualitatively predict excited state dynamics in perylene.
• The study highlights the importance of methodological refinement for accurate photophysical property calculations.
• PBE0/def2-TZVP shows promise for accurate PLQY and AKQY predictions in perylene.