Quantum simulations of thermally activated delayed fluorescence in an all-organic emitter

We investigate the prototypical NAI-DMAC thermally activated delayed fluorescence (TADF) emitter in the gas phase- and high-packing fraction limits at finite temperature, by combining first principles molecular dynamics with a quantum thermostat to account for nuclear quantum effects (NQE). We find...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2022-05, Vol.24 (17), p.111-1113
Main Authors: Francese, Tommaso, Kundu, Arpan, Gygi, Francois, Galli, Giulia
Format: Article
Language:English
Subjects:
Electronic properties
Emitters
Energy gap
First principles
Fluorescence
Molecular dynamics
Optimization
Oscillator strengths
Temperature dependence
Temperature effects
Transition probabilities
Vapor phases
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Summary:We investigate the prototypical NAI-DMAC thermally activated delayed fluorescence (TADF) emitter in the gas phase- and high-packing fraction limits at finite temperature, by combining first principles molecular dynamics with a quantum thermostat to account for nuclear quantum effects (NQE). We find a weak dependence of the singlet-triplet energy gap (Δ E ST ) on temperature in both the solid and the molecule, and a substantial effect of packing. While the Δ E ST vanishes in the perfect crystal, it is of the order of ∼0.3 eV in the molecule, with fluctuations ranging from 0.1 to 0.4 eV at 300 K. The transition probability between the HOMOs and LUMOs has a stronger dependence on temperature than the singlet-triplet gap, with a desirable effect for thermally activated fluorescence; such temperature effect is weaker in the condensed phase than in the molecule. Our results on ΔE ST and oscillator strengths, together with our estimates of direct and reverse intersystem crossing rates, show that optimization of packing and geometrical conformation is critical to increase the efficiency of TADF compounds. Our findings highlight the importance of considering thermal fluctuations and NQE to obtain robust predictions of the electronic properties of NAI-DMAC. The prototypical NAI-DMAC TADF emitter is investigated in the gas phase- and high-packing fraction limits at finite temperature, by combining first principles molecular dynamics with a quantum thermostat to account for nuclear quantum effects (NQE).
ISSN:1463-9076
1463-9084
DOI:10.1039/d2cp01147f