A compact model system for electron–phonon calculations in discotic materials

Kruglova, Olga; Mulder, Fokko M.; Kotlewski, A.; Picken, Stephen J.; Parker, Stewart F.; Johnson, Mark R.; Kearley, Gordon J.

doi:10.1016/j.chemphys.2006.09.006

Cited by 13 publications

(12 citation statements)

References 13 publications

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“…Previous studies of the HAT 6 have shown that structure and dynamics play a central role in the charge-transfer process of these materials. It was noted that the dynamics of the aromatic cores and the alkyl tails can affect the electronic properties [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Density functional calculations of potential energy surface and charge transfer integrals in molecular triphenylene derivative HAT6

et al. 2009

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We investigate the effect of structural fluctuations on charge transfer integrals, overlap integrals, and site energies in a system of two stacked molecular 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT 6 ), which is a model system for conducting devices in organic photocell applications. A density functional based computational study is reported. Accurate potential energy surface calculations are carried out using an improved meta-hybrid density functional to determine the most stable configuration of the two weakly bound HAT 6 molecules. The equilibrium parameters in terms of the twist angle and co-facial separation are calculated. Adopting the fragment approach within the Kohn-Sham density functional framework, these parameters are combined to a lateral slide, to mimic structural/ conformational fluctuations and variations in the columnar phase. The charge transfer and spatial overlap integrals, and site energies, which form the matrix element of the Kohn-Sham Hamiltonian are derived. It is found that these quantities are strongly affected by the conformational variations. The spatial overlap between stacked molecules is found to be of considerable importance since charge transfer integrals obtained using the fragment approach differ significantly from those using the dimer approach.

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Section: Introductionmentioning

confidence: 99%

Density functional calculations of potential energy surface and charge transfer integrals in molecular triphenylene derivative HAT6

et al. 2009

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“…Electron-phonon coupling in as elf-assembling discotic material was the topic of as tudy by Kruglova et al [9] The electron-phonon coupling underlies unwanted excited state relaxation in these organic molecules,which function not only as hole conductors,b ut also as light-absorbing dyes.U nderstanding this unwanted decay of excited states is another of the key areas of interest within organic electronics research. Theg roup studied af amily of related triphenylene derivatives,each comprising alkoxy substitents of different lengths, again with the aim of understanding the minimum theoretical model necessary to accurately describe the vibrational dynamics of the system.…”

Section: Angewandte Chemiementioning

confidence: 99%

“…The observed (top) and calculated (bottom) INS spectra for HAT1D, emphasising the ability to readily simulate neutron spectra theoretically.Reproduced with permission from ref [9]…”

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Neutron Spectroscopy: An Under‐Utilised Tool for Organic Electronics Research?

Cavaye

2019

Angewandte Chemie

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Neutron scattering is a well‐established technique that has proven to be an invaluable tool in myriad fields of chemical and physical research. Neutrons offer unique ways to study in situ or operando functional materials due to their highly penetrating nature and specific interactions with the nuclei of different isotopes. While some neutron scattering techniques, such as neutron diffraction (ND), neutron reflectometry (NR), and small‐angle neutron scattering (SANS), have already been heavily adopted by the scientific community for use in the research of organic electronics, there are a number of techniques that are far less widely used: spectroscopic neutron scattering. This article aims to highlight these “under‐utilised” techniques, to emphasise their potential use within the field of organic electronics, and to increase awareness of their utility among new research communities.

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“…23,33 The charge transfer compounds were obtained by mixing HAT6 (or HAT6D) with 2,4,7-trinitro-9-fluorenone (TNF) in a 1:1 molar proportion in dichloromethane. 23 The mixture was subsequently evaporated to dryness at room temperature.…”

Section: A Sample Preparationmentioning

confidence: 99%

Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex

Haverkate

Zbiri

Johnson

et al. 2014

The Journal of Chemical Physics

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Discotic liquid crystalline (DLC) charge transfer (CT) complexes combine visible light absorption and rapid charge transfer characteristics, being favorable properties for photovoltaic (PV) applications. We present a detailed study of the electronic and vibrational properties of the prototypic 1:1 mixture of discotic 2,3,6,7,10,11-hexakishexyloxytriphenylene (HAT6) and 2,4,7-trinitro-9-fluorenone (TNF). It is shown that intermolecular charge transfer occurs in the ground state of the complex: a charge delocalization of about 10 −2 electron from the HAT6 core to TNF is deduced from both Raman and our previous NMR measurements (2012)], implying the presence of permanent dipoles at the donor-acceptor interface. A combined analysis of density functional theory calculations, resonant Raman and UV-VIS absorption measurements indicate that fast relaxation occurs in the UV region due to intramolecular vibronic coupling of HAT6 quinoidal modes with lower lying electronic states. Relatively slower relaxation in the visible region the excited CT-band of the complex is also indicated, which likely involves motions of the TNF nitro groups. The fast quinoidal relaxation process in the hot UV band of HAT6 relates to pseudo-Jahn-Teller interactions in a single benzene unit, suggesting that the underlying vibronic coupling mechanism can be generic for polyaromatic hydrocarbons. Both the presence of ground state CT dipoles and relatively slow relaxation processes in the excited CT band can be relevant concerning the design of DLC based organic PV systems.

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A compact model system for electron–phonon calculations in discotic materials

Cited by 13 publications

References 13 publications

Density functional calculations of potential energy surface and charge transfer integrals in molecular triphenylene derivative HAT6

Density functional calculations of potential energy surface and charge transfer integrals in molecular triphenylene derivative HAT6

Neutron Spectroscopy: An Under‐Utilised Tool for Organic Electronics Research?

Electronic and vibronic properties of a discotic liquid-crystal and its charge transfer complex

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