Singlet Exciton Fission in a Hexacene Derivative

Lee, Jiye; Bruzek, Matthew J.; Thompson, Nicholas J.; Sfeir, Matthew Y.; Anthony, John E.; Baldo, Marc A.

doi:10.1002/adma.201203982

Cited by 73 publications

(83 citation statements)

References 25 publications

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“…24 In contrast, Lee et al reported a time constant of ∼5.1 ps for singlet fission in thin films of a tricyclohexylsilylethynyl-substituted Hn derivative. 126 Significantly, these films exhibited at least an order-ofmagnitude smaller redshift of the lowest-energy singlet transition, suggesting that they comprise primarily weakly coupled chromophores. Thus, it is apparent that weak excitonic Figure 8.…”

Section: Journal Of the American Chemical Societymentioning

confidence: 98%

Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives

et al. 2015

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We compare the singlet fission dynamics of five pentacene derivatives precipitated to form nanoparticles. Two nanoparticle types were distinguished by differences in their solid-state order and kinetics of triplet formation. Nanoparticles that comprise primarily weakly coupled chromophores lack the bulk structural order of the single crystal and exhibit nonexponential triplet formation kinetics (Type I), while nanoparticles that comprise primarily more strongly coupled chromophores exhibit order resembling that of the bulk crystal and triplet formation kinetics associated with the intrinsic singlet fission rates (Type II). In the highly ordered nanoparticles, singlet fission occurs most rapidly. We relate the molecular packing arrangement derived from the crystal structure of the pentacene derivatives to their singlet fission dynamics and find that slip stacking leads to rapid, subpicosecond singlet fission. We present evidence that exciton delocalization, coincident with an increased relative admixture of charge-transfer configurations in the description of the exciton wave function, facilitates rapid triplet pair formation in the case of single-step singlet fission. We extend the study to include two hexacene derivatives and find that these conclusions are generally applicable. This work highlights acene derivatives as versatile singlet fission chromophores and shows how chemical functionalization affects both solid-state order and exciton interactions and how these attributes in turn affect the rate of singlet fission.

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Section: Journal Of the American Chemical Societymentioning

confidence: 98%

Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives

et al. 2015

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“…20,21,23,27,[30][31][32] Although this two-molecule picture is indeed a minimal model for singlet fission, it must be questioned whether such a model is quantitatively-or even qualitatively-relevant for experimental investigations in crystalline materials. It must be kept in mind that essentially all reported experimental findings of rapid and efficient singlet fission occur in the crystal phase 10,11,[13][14][15][16][17][18][19] whereas singlet fission in covalent dimers in solution has been reported with vanishingly small yield. 33,34 Between single molecules and bulk crystals, there exist large variations in basic experimental signatures of electronic energy levels, including ionization energies and absorption spectroscopies, which already hints at the potential differences between these two classes of materials.…”

Section: Introductionmentioning

confidence: 97%

“…1,2 When combined with a secondary absorbing material, this type of multiple exciton generation 3 can boost the maximal power conversion efficiency of a solar cell to 45%, 4 well above the ShockleyQueisser limit of 31%. 5 Despite a significant number of experimental [6][7][8][9][10][11][12][13][14][15][16][17][18][19] and theoretical 20-32 studies on a wide range of materials, the microscopic mechanism by which singlet fission takes place is still a matter of debate. The status of the field has been expertly summarized by Smith and Michl in Ref.…”

Section: Introductionmentioning

confidence: 99%

Microscopic theory of singlet exciton fission. III. Crystalline pentacene

Berkelbach

Hybertsen

Reichman

2014

The Journal of Chemical Physics

174

247

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We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems.

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“…On the theory side, oligoacenes have been subject of an intensive debate due to pronounced correlation effects 3,4 . Much of the interest in this class of molecules is driven by organic electronics 5 and photovoltaics 6,7 , where oligoacenes and their derivatives find frequent applications [8][9][10][11][12] . From a broader perspective, a study of systems with linearly fused rings, 'nanographenes', offers means to learn how properties of a molecular wire converge to the one-dimensional limit.…”

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confidence: 99%

Signature of the Dirac cone in the properties of linear oligoacenes

et al. 2014

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Organic electronics offers prospects of functionality for science, industry and medicine that are new as compared with silicon technology and available at a very low material cost. Among the plethora of organic molecules available for materials design, polymers and oligomers are very promising, for example, because of their mechanical flexibility. They consist of repeated basic units, such as benzene rings, and the number of these units N determines their excitation gap, a property that is often used in proposals of organic photovoltaics. Here, we show that contrary to a widely held belief the magnitudes of excitation gaps do not always decay monotonously with N, but can oscillate due to the presence of a 'Dirac cone' in the band structure. With an eye on the more fundamental question how a molecular wire becomes metallic with increasing length, our research suggests that the process can exhibit incommensurate oscillations.

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Singlet Exciton Fission in a Hexacene Derivative

Cited by 73 publications

References 25 publications

Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives

Exciton Delocalization Drives Rapid Singlet Fission in Nanoparticles of Acene Derivatives

Microscopic theory of singlet exciton fission. III. Crystalline pentacene

Signature of the Dirac cone in the properties of linear oligoacenes

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