Towards multistate multimode landscapes in singlet fission of pentacene: the dual role of charge-transfer states

Walia, Rajat; Deng, Zexiang; Yang, Jun

doi:10.1039/d1sc01703a

Cited by 7 publications

(7 citation statements)

References 90 publications

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“…To examine the spectral manifestation of mixed states in MesPcHex at 77 K, EADS were obtained (Figure S33). Notably, the extent of mixing with charge transfer (CT) configurations was reduced at lower temperature, as evidenced by the initial and intermediate EADS at 77 K. The observation suggests that structural motions may play an important role in the mixing between FE/TT and CT states, as supported by theoretical studies. − The diminished CT character at low temperature likely contributes to the slower kinetics of the first step in the biphasic excited-state dynamics. Furthermore, the efficient TT generation in MesPcHex can be attributed to the increased entropy contribution, resulting from the presence of multiple TT microstates within the tightly packed hexamer. , Further details can be found in the supplementary note in Figure S33.…”

Section: Resultsmentioning

confidence: 81%

Leveraging Charge-Transfer Interactions in Through-Space-Coupled Pentacene Dendritic Oligomer for Singlet Exciton Fission

Kim,

Teo,

Hong

et al. 2023

J. Am. Chem. Soc.

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Singlet exciton fission in organic chromophores has received much attention during the past decade. Inspired by numerous spectroscopic studies in the solid state, there have been vigorous efforts to study singlet exciton fission dynamics in covalently bonded oligomers, which aims to investigate underlying mechanisms of this intriguing process in simplified model systems. In terms of through-space orbital interactions, however, most of covalently bonded pentacene oligomers studied so far fall into weakly interacting systems since they manifest chain-like structures based on various (non)conjugated linkers. Therefore, it remains as a compelling question to answer how through-space interactions in the solid state intervene this photophysical process since it is hypersensitive to displacements and orientations between neighboring chromophores. Herein, as one of experimental studies to answer this question, we introduced a tight-packing dendritic structure whose mesityl-pentacene constituents are coupled via moderate through-space orbital interactions. Based on the comparison with a suitably controlled dendritic structure, which is in a weak coupling regime, important mechanistic viewpoints are tackled such as configurational mixings between singlet, charge-transfer, and triplet pair states and the role of chromophore multiplication. We underscore that our through-space-coupled dendritic oligomer in a quasi-intermediate coupling regime provides a hint on the interplay of multiconfigurational excited-states, which might have drawn complexity in singlet exciton fission kinetics throughout numerous solid-state morphologies.

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Section: Resultsmentioning

confidence: 81%

Leveraging Charge-Transfer Interactions in Through-Space-Coupled Pentacene Dendritic Oligomer for Singlet Exciton Fission

Kim,

Teo,

Hong

et al. 2023

J. Am. Chem. Soc.

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“…We, however, exclude this possibility because aggregation/crystallinity of TIPS-PEN would result in a significant broadening of spectral features, the formation of additional absorption background on the red side of the S 0 –S 1 transition, and the appearance of distinct low-energy Raman modes below 200 cm – 1 , which were not observed. Therefore, molecules in the considered samples are only weakly coupled to each other, and therefore, vibronic promotion of SF is still likely. , …”

Section: Resultsmentioning

confidence: 99%

“…This is not surprising since the exothermic nature of SF in TIPS-PEN makes such loss as triplet−triplet annihilation energetically unfavorable. 46 The generation of triplet excitons is likely mediated by vibrationally promoted intermolecular interactions of CT character 38,42,47,48 or low-lying states of a dimer-like exciton. 49 Interestingly, the intensity borrowing by species B from species A started at the low-energy side of the broad S 1 -ESA spectrum.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Charge-Transfer States at Metal–Organic Interface Limit Singlet Fission Yields: A Photonically Enhanced Pump–Probe Study

Kolesnichenko,

Hertzog,

Hainer

et al. 2024

J. Phys. Chem. C

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Singlet fission is an exciton-multiplication process that holds promise for next-generation photovoltaic applications. While triplet yields of up to 200% have been reported in thin films of organic fission materials, photovoltaic applications require metal contacts for the generation of photocurrents, which are likely to be impacted not only by triplet fusion and singlet recombination but also by voltage losses at the metal–organic interface and photonic (Purcell) enhancement. Here, we study a series of thin layers of 6,13-bis(triisopropylsilylethynyl)pentacene on silver contacts in open-cavity geometry by using Purcell-enhanced pump–probe spectroscopy. Facilitated by the photonic enhancement, we are able to detect interfacial charge-transfer states and conclude that a significant fraction (40%) of correlated triplet excitons is lost at the metal–organic interface. We further find that although transition rates of singlet fission steps vary with variations of photonic environment, nevertheless, due to the competing nature of channels leading to triplet formation and loss, the resulting singlet fission yields remain unchanged. This is further supported by target analysis of time-resolved spectra and transfer-matrix simulations. These insights on the essential interactions between singlet fission materials in the proximity of metallic contacts are pivotal for the photovoltaic utilization of singlet fission, as efficient extraction of photoexcitations is key to maximizing solar energy harvest.

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“…Later, a projection approximation scheme was further incorporated to reduce the cost of evaluating the norm and energy expectation value for the most expensive classes of perturber functions. Recently, DMRG-sc-NEVPT2 was successfully applied to the investigation of magnetic exchange couplings in bis-μ-oxo/μ-acetato Mn(III, IV) dimer, intra- and intermolecular singlet fission (SF) , as well as carotenoid nuclear reorganization . However, it may also be noted that a recent benchmark comparison for RDM approximations in NEVPT2 by Guo et al . , indicates that the abuse of cumulant approximation always leads to intruder states, while the prescreening approximation produces stable results with modest computational savings.…”

Section: Mps-dmrgmentioning

confidence: 99%

Post-Density Matrix Renormalization Group Methods for Describing Dynamic Electron Correlation with Large Active Spaces

Cheng

Xie

2022

J. Phys. Chem. Lett.

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The ab initio density matrix renormalization group (DMRG) method has been well-established and has become one of the most accurate numerical methods for the precise electronic structure solution of large active spaces. In the past few years, to capture the missing dynamic correlation, various post-DMRG approaches have been proposed through the combination of DMRG and multireference quantum chemical methods or density functional theory. With this in mind, this work provides a brief overview of ab initio DMRG principles and the new developments within post-DMRG methods. For clarity, post-DMRG methods are classified into two main categories depending on whether high-order n-electron reduced density matrices are used, and their merits and disadvantages are properly discussed. Finally, we conclude by discussing unsolved bottlenecks and giving development perspectives of post-DMRG approaches, which are expected to yield quantitative descriptions of complex electronic structures in large strongly correlated molecules and materials.

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Towards multistate multimode landscapes in singlet fission of pentacene: the dual role of charge-transfer states

Abstract: Singlet fission duplicates triplet excitons for improving light harvesting efficiency. The presence of the interaction between electronic and nuclear degrees of freedom complicates the interpretation of correlated triplet pairs. We...

Cited by 7 publications

References 90 publications

Leveraging Charge-Transfer Interactions in Through-Space-Coupled Pentacene Dendritic Oligomer for Singlet Exciton Fission

Leveraging Charge-Transfer Interactions in Through-Space-Coupled Pentacene Dendritic Oligomer for Singlet Exciton Fission

Charge-Transfer States at Metal–Organic Interface Limit Singlet Fission Yields: A Photonically Enhanced Pump–Probe Study

Post-Density Matrix Renormalization Group Methods for Describing Dynamic Electron Correlation with Large Active Spaces

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