The Nature of Singlet Exciton Fission in Carotenoid Aggregates

Musser, Andrew J.; Maiuri, Margherita; Brida, Daniele; Cerullo, Giulio; Friend, Richard H.; Clark, Jenny

doi:10.1021/jacs.5b01130

Cited by 159 publications

(243 citation statements)

References 57 publications

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“…Finally, a very recent model suggests that the non-interacting T 1 states are directly populated from the absorbing state without the participation of any intermediate electronic state in the process. 62 In the present contribution, we have designed and examined two novel pentacene dimers XC1 and XC2, that feature a cross-conjugated framework to mediate the electronic coupling between the two pentacene moieties. The cross-conjugated structural modification is expected to be particularly helpful as a means to either enhance or attenuate the through bond electronic couplings between the pentacene chromophores.…”

Section: 17mentioning

confidence: 99%

Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers

et al. 2016

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aWe show unambiguous and compelling evidence by means of pump-probe experiments, which are complemented by calculations using ab initio multireference perturbation theory, for intramolecular singlet fission (SF) within two synthetically tailored pentacene dimers with cross-conjugation, namely XC1 and XC2. The two pentacene dimers differ in terms of electronic interactions as evidenced by perturbation of the ground state absorption spectra stemming from stronger through-bond contributions in XC1 as confirmed by theory. Multiwavelength analysis, on one hand, and global analysis, on the other hand, confirm that the rapid singlet excited state decay and triplet excited state growth relate to SF. SF rate constants and quantum yields increase with solvent polarity. For example, XC2 reveals triplet quantum yields and rate constants as high as 162 ± 10% and (0.7 ± 0.1) × 10 12 s −1, respectively, in room temperature solutions.

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Section: 17mentioning

confidence: 99%

Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers

et al. 2016

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“…In particular, their photophysical properties change dramatically with the environment due to the formation of different types of aggregates. 7,8 As many other carotenoids and chlorophylls, [9][10][11] AXT also forms aggregates when dissolved in hydrated polar solvents. 8,12 The water concentration in these mixtures influences the morphology of the aggregates, and, consequently, their properties.…”

Section: 4mentioning

confidence: 99%

“…7,8 As many other carotenoids and chlorophylls, [9][10][11] AXT also forms aggregates when dissolved in hydrated polar solvents. 8,12 The water concentration in these mixtures influences the morphology of the aggregates, and, consequently, their properties. In particular, spectroscopic analysis have shown that their absorption spectra can be blue shifted as well as red shifted compared to that of the isolated monomers depending on the aggregation conditions.…”

Section: 4mentioning

confidence: 99%

“…In particular, spectroscopic analysis have shown that their absorption spectra can be blue shifted as well as red shifted compared to that of the isolated monomers depending on the aggregation conditions. 7,8,[12][13][14] The blue shift is attributed to the formation of H-aggregates and the red shift is attributed to the formation of J-aggregates. The H-aggregates formed by these molecules when deposited on surfaces or arranged at interfaces, hold promise as photoactive species in dye-sensitized solar cells.…”

Section: 4mentioning

confidence: 99%

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Molecular Properties of Astaxanthin in Water/Ethanol Solutions from Computer Simulations

2016

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Astaxanthin (AXT) is a reference model of xanthophyll carotenoids, which is used in medicine and food industry, and has potential applications in nanotechnology. Because of its importance, there is a great interest in understanding its molecular properties and aggregation mechanism in water and mixed solvents. In this paper, we report a novel model of AXT for molecular dynamics simulation. The model is used to estimate different properties of the molecule in pure solutions and in water/ethanol mixtures. 1The calculated diffusion coefficients of AXT in pure water and ethanol are (3.22 ± 0.01) × 10 −6 cm 2 s −1 and (2.7 ± 0.4) × 10 −6 cm 2 s −1 , respectively.Our simulations also show that the content of water plays a clear effect on the morphology of the AXT aggregation in water/ethanol mixture. In up to 75% (v/v) water concentration, loosely connected network of dimers and trimers, and two-dimensional array structures are observed. At higher water concentrations, AXT molecules form more compact three-dimensional structures that are preferentially solvated by the ethanol molecules. The ethanol preferential binding and the formation of a well connected hydrogen bonding network on these AXT clusters, suggest that such preferential solvation can play an important role in controlling the aggregate structure.

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“…In the literature, there exist only a few studies which go beyond frontier molecular orbitals approximation [13][14][15][16][17][18][19][20][21] . The polyene systems are important model molecules and there are several reports which indicate singlet fission in carotenoids and polyene systems [21][22][23][24][25][26][27][28] . We start with a wave packet formed from the ground state of one molecule and the singlet excited state of another, these states being the exact eigenstates of the molecule within the chosen model Hamiltonians.…”

Section: Introductionmentioning

confidence: 99%

Exact wave packet dynamics of singlet fission in unsubstituted and substituted polyene chains within long-range interacting models

Prodhan

Ramasesha

2017

Phys. Rev. B

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Singlet fission (SF) is a potential pathway for significant enhancement of efficiency in organic solar cells (OSC). In this paper, we study singlet fission in a pair of polyene molecules in two different stacking arrangements employing exact many-body wave packet dynamics. In the noninteracting model, the SF yield is absent. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interaction between them involves transfer terms, intersite electron repulsions and site-charge-bond-charge repulsion terms. Initial wave packet is constructed from excited singlet state of one molecule and ground state of the other. Time development of this wave packet under the influence of intermolecular interactions is followed within the Schrödinger picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, 2 1 A excited singlet state leads to significant SF yield while the 1 1 B state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, the lowest excited state will have sufficient 2 1 A character and hence results in significant SF yield. Because of rapid internal conversion, the nature of the lowest excited singlet will determine the SF contribution to OSC efficiency. Furthermore, we find the fission yield depends considerably on the stacking arrangement of the polyene molecules.

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The Nature of Singlet Exciton Fission in Carotenoid Aggregates

Cited by 159 publications

References 57 publications

Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers

Solution-based intramolecular singlet fission in cross-conjugated pentacene dimers

Molecular Properties of Astaxanthin in Water/Ethanol Solutions from Computer Simulations

Exact wave packet dynamics of singlet fission in unsubstituted and substituted polyene chains within long-range interacting models

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