Tuning Nonradiative Lifetimes via Molecular Aggregation

Celestino, Alan; Eisfeld, Alexander

doi:10.1021/acs.jpca.7b06259

Cited by 10 publications

(8 citation statements)

References 52 publications

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“…67 Also the interaction between molecules might change the corresponding rate constants. 68 Furthermore, several additional non-radiative de-excitation mechanisms are possible. These are in particular exciton-exciton annihilation (EEA) and singlet fission (SF).…”

Section: Quantum Yield Of Fluorescencementioning

confidence: 99%

Excitation dynamics in polyacene molecules on rare-gas clusters

Bohlen,

Michiels,

Michelbach

et al. 2022

Preprint

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Laser-induced fluorescence spectra and excitation lifetimes of anthracene, tetracene, and pentacene molecules attached to the surface of solid argon clusters have been measured with respect to cluster size, density of molecules and excitation density.Results are compared to previous studies on the same sample molecules attached to neon clusters. A contrasting lifetime behavior of anthracene on neon and argon clusters is discussed, and mechanisms are suggested to interpret the results. Although both neon and argon clusters are considered to be weakly interacting environments, we find that the excitation decay dynamics of the studied acenes depends significantly on the cluster material. Moreover, we find even qualitative differences regarding the dependence on the dopant density. Based on these observations, previous assignments of collective radiative and non-radiative decay mechanisms are discussed in the context of the new experimental findings.

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Section: Quantum Yield Of Fluorescencementioning

confidence: 99%

Excitation dynamics in polyacene molecules on rare-gas clusters

Bohlen,

Michiels,

Michelbach

et al. 2022

Preprint

Self Cite

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“…Hence, the key to calculate the rate is to calculate the time correlation function (TCF) shown in Eq. (9).…”

Section: A Hamiltonian and Transition Ratementioning

confidence: 99%

“…Considering the important role of NRER in the molecular photophysical processes, how to calculate the rate of NRER theoretically has always been a hot topic. [2][3][4][5][6][7][8][9] Currently, the real-time nonadiabatic dynamics simulation and the rate theory relying on the Fermi's golden rule (FGR) are the two main approaches to study NRER process. Nonadiabatic dynamics directly simulate the nuclear motions over the coupled potential energy surfaces (PES) to obtain the real-time population on each electronic state.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Anharmonicity Contributions to the Molecular Excited State Internal Conversion Rates with Finite Temperature TD-DMRG

Wang¹,

Ren

Shuai³

2021

Preprint

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<div>In this work, we propose a new method to calculate the molecular nonradiative electronic relaxation rates based on the numerically exact time-dependent density matrix renormalization group theory (TD-DMRG). This method could go beyond the existing frameworks under the harmonic approximation (HA) of the potential energy surface (PES) so that the important anharmonic effect could be considered when large electronic energy is transferred into the vibrations to excite them to the high energy levels. The effectiveness and scalability of the method are verified in calculating the internal conversion (IC) rate of azulene by comparing it with the analytically exact results under HA. Furthermore, we investigate the validity of HA in a two-mode model with Morse potential. We find that HA is unsatisfactory unless only the lowest several vibrational states of the lower electronic state are involved in the transition process when the adiabatic excitation energy is relatively low. As the excitation energy increases, HA first underestimates and then overestimates the IC rates when the excited state PES shifts towards the dissociative side of the ground state PES. On the contrary, HA slightly overestimates the IC rates when the excited state PES shifts towards the repulsive side. In both cases, higher temperature enlarges the error of HA. <br></div>

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“…However, due to the inherent electron-phonon coupled many-body problem, the affordable system size and accuracy are quite limited. The current explorations in this direction are mainly restricted to demonstrative dimer models 15,16 and the results are hard to unify. Li et al found that non-radiative decay is enhanced by excitonic coupling in both J-aggregates and H-aggregates as predicted by EGL.…”

Section: Introductionmentioning

confidence: 99%

Minimizing non-radiative decay in molecular aggregates through optimal control of excitonic coupling

Wang

Ren

Shuai

2022

Preprint

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The widely known ``Energy Gap Law'' (EGL) predicts a monotonically exponential increase in the non-radiative decay rate (knr) as the energy gap narrows, which hinders the development of near-infrared (NIR) emissive molecular materials. Recently, several experiments proposed that the exciton delocalization in molecular aggregates could counteract EGL to facilitate NIR emission. In this work, the nearly exact time-dependent density matrix renormalization group (TD-DMRG) method is developed to evaluate the non-radiative decay rate for exciton-phonon coupled molecular aggregates. Systematical numerical simulations show, by increasing the excitonic coupling, knr will first decrease, then reach a minimum, and finally start to increase to follow the EGL, which is an overall result of two opposite effects of a smaller energy gap and a smaller effective electron-phonon coupling. This anomalous non-monotonic behavior is found robust in a number of models, including dimer, one-dimensional chain, and two-dimensional square lattice. The optimal excitonic coupling strength that gives the minimum knr is about half of the monomer reorganization energy and is also influenced by temperature, system size, and dimensionality.

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Tuning Nonradiative Lifetimes via Molecular Aggregation

Cited by 10 publications

References 52 publications

Excitation dynamics in polyacene molecules on rare-gas clusters

Excitation dynamics in polyacene molecules on rare-gas clusters

Evaluating the Anharmonicity Contributions to the Molecular Excited State Internal Conversion Rates with Finite Temperature TD-DMRG

Minimizing non-radiative decay in molecular aggregates through optimal control of excitonic coupling

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