Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Manian, Anjay; Shaw, Robert A.; Lyskov, Igor; Wong, Wallace W. H.; Russo, Salvy P.

doi:10.1063/5.0058643

Cited by 12 publications

(74 citation statements)

References 89 publications

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“…In addition to the exciton transport, we also need to model the processes that result in loss of the electron-hole quasiparticle, such as charge recombination, internal conversion (IC) and inter-system crossing (ISC). These latter two are relaxation processes mediated by heat, in which heat is exchanged with the environment when spin is and is not conserved 13,14 respectively.…”

Section: A Transport Modelmentioning

confidence: 99%

“…Each process is dependant on different photophysical coupling terms: fluorescence on the transition dipole moment, IC on vibronic coupling between singlet states, and ISC the spin-orbit coupling between singlet and triplet states. These rate constants can be very difficult to compute, however we have recently developed a methodology to do so at the Time-Dependant Density Functional Theory (TDDFT) level of theory 14 .…”

Section: A Transport Modelmentioning

confidence: 99%

“…Quantum chemically optimised geometries of the relevant excited states, rate constants, and photophysical properties of PDI and tetracene were computed as per our previous study 14 .…”

Section: B Quantum Chemistrymentioning

confidence: 99%

“…Other sources of loss include photons escaping the device 11 upon fluorescence, and the intrinsic photoluminescence quantum yield (PLQY) loss, i.e., the probability of fluorescence of the host chromophore. Previously, we have investigated the parameters behind excitonic quenching [12][13][14] , providing us a strong foundation with which to consider the processes within a given device.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we focus on exciton migration through a medium such as an LSC. To do so, we use a KMC method based on transition rates that we obtain from quantum chemical calculations 14 . KMC methods have been used in surface based simulations 32 , and exciton diffusion/hopping studies 33 , making it an ideal tool for our purpose.…”

Section: Introductionmentioning

confidence: 99%

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Singlet exciton dynamics of perylene diimide and tetracene based hetero/homogeneous substrates via an \textit{ab initio} kinetic Monte Carlo model

Manian¹,

Campaioli²,

Lyskov³

et al. 2021

Preprint

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Luminescent solar concentrators (LSCs) are devices that trap a portion of the solar spectrum and funnel it towards photon harvesting devices. The modelling of LSCs at a quantum chemical level however, remains a challenge due to the complexity of exciton and photon dynamic modelling. This study examines singlet exciton dynamics occurring within a typical LSC device. To do this, we use a rejection-free kinetic Monte Carlo method to predict diffusion lengths, diffusion coefficients, substrate anisotropy, and average exciton lifetimes of perylene diimide (PDI) and tetracene based substrates in the low concentration scheme. Ab initio rate constants are computed using time-dependant density functional theory based methods. PDI type substrates are observed to display enhanced singlet exciton transport properties when compared to tetracene. Simulations show that substrates with dipole-aligned chromophores are characterised by anisotropic exciton diffusion, with slightly improved transport properties. Finally, a PDI-tetracene substrate is simulated for both disordered and dipole-aligned chromophore configurations. In this multi-dopant substrate transport is predominantly mediated by PDI due to the asymmetry in the transport rates between the two dyes considered. We conclude discussing the properties of multi-dopant substrates and how they can impact the design of next generation LSCs.

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Section: A Transport Modelmentioning

confidence: 99%

Section: A Transport Modelmentioning

confidence: 99%

“…Quantum chemically optimised geometries of the relevant excited states, rate constants, and photophysical properties of PDI and tetracene were computed as per our previous study 14 .…”

Section: B Quantum Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Singlet exciton dynamics of perylene diimide and tetracene based hetero/homogeneous substrates via an \textit{ab initio} kinetic Monte Carlo model

Manian¹,

Campaioli²,

Lyskov³

et al. 2021

Preprint

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Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Manian,

Campaioli,

Hudson

et al. 2023

Chem. Mater.

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The role of charge transfer states in multi-exciton mechanisms has recently become a point of discussion due to the difficulty associated with modeling their contributions accurately. Intermolecular packing has been shown experimentally to heavily influence multi-exciton mechanisms, and therefore understanding how this affects the coupling is key to controlling these processes. Using a gas phase perylene dimer in a weakly coupled configuration as a case study, we employ two separate methods to model the coupling between the bright and correlated triplet 1 TT states as a function of relative displacement. For singlet fission, displaced geometries are found to yield large charge transfer contributions within a wavefunction overlap paradigm, unlike for aligned geometries. Triplet−triplet annihilation charge transfer couplings are conversely very weak due to a large energy gap. We found that slipping of the dimer cofacial geometry is beneficial to both charge transfer-mediated processes within a wavefunction overlap scheme. However, within a fragment excitation difference (FED) scheme, a 1 Å slip is more beneficial than a 2 Å one. The resulting rates for singlet fission are in the femtosecond range, up to 22 ps −1 , while for triplet fusion they are in the nanosecond range, up to 707 μs −1 . By studying the dynamics of the triplet pair following singlet fission, we show that the decorrelation time scale depends on the nature of the relative molecular motion, ranging from picoseconds for fluctuations in the monomer orientations to microseconds for coplanar fluctuations. The direct comparison of the wavefunction overlap and FED methods yields an expected differential due to the method of calculation (linear-response vs multireference) but still strong agreement, suggesting that the more exact wavefunction overlap method can be substituted for the FED method in larger systems with minimal loss in accuracy vs computational complexity. These results provide a good stepping stone for further investigations into singlet fission related problems, correlating well with experiments despite the weakly coupled nature of the dimer.

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Exciton Dynamics of a Diketo-Pyrrolopyrrole Core for All Low-Lying Electronic Excited States Using Density Functional Theory-Based Methods

Manian

Shaw

Lyskov

et al. 2022

J. Chem. Theory Comput.

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Ab initio treatments of interexcited state internal conversion (IC) are more often than not missing from exciton dynamic descriptions, because of their inherent complexity. Here, we define "interexcited state IC" as a same-spin nonradiative transition between states i and j, where i ≠ j ≠ 0. Competing directly with multiexciton processes such as singlet fission or triplet photoupconversion, inclusion of this mechanism in the narrative of molecular photophysics would allow for strategic synthesis of chromophores for more efficient photon-harvesting applications. Herein, we present a robust formalism which can model these rates using density functional theory (DFT)-based methods within the Franck−Condon and Herzberg−Teller regime. Using an unsubstituted diketopyrrolopyrrole (DPP) core as a case study, we illustrate the exciton dynamics along the first four excited states for both singlet and triplet manifolds, showing ultrafast same-spin transfer mechanisms due to all excited states, excluding the first triplet level, being in close energetic proximity (within 0.8 eV of each other). The resulting electron same-spin rates outcompete the electron spin-flipping intersystem crossing (ISC) rates, with excitons firmly obeying Kasha's rule as they cascade down from the high-lying excited states toward the lower states. Furthermore, we calculated that only the first singlet excited state displayed a reasonable probability of triplet exciton generation, of ∼40%, with a near-zero chance of the exciton reverting to the singlet manifold once the electron−hole pair are of parallel spin.

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Modeling radiative and non-radiative pathways at both the Franck–Condon and Herzberg–Teller approximation level

Cited by 12 publications

References 89 publications

Singlet exciton dynamics of perylene diimide and tetracene based hetero/homogeneous substrates via an \textit{ab initio} kinetic Monte Carlo model

Singlet exciton dynamics of perylene diimide and tetracene based hetero/homogeneous substrates via an \textit{ab initio} kinetic Monte Carlo model

Charge Transfer-Mediated Multi-exciton Mechanisms in Weakly Coupled Perylene Dimers

Exciton Dynamics of a Diketo-Pyrrolopyrrole Core for All Low-Lying Electronic Excited States Using Density Functional Theory-Based Methods

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