Spectroscopic Evidence for a Substrate Dependent Orientation of Sexithiophene Thin Films Deposited onto Oriented PTFE

Lang, Philippe; Horowitz, Gilles; Valat, P.; Garnier, F.; Wittmann, J. C.; Lotz, Bernard

doi:10.1021/jp9701303

Cited by 33 publications

(27 citation statements)

References 44 publications

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“…For this reason, a wide variety of experimental investigations have been performed on these systems. The electronic properties of oligothiophenes in the solid state − have particularly retained the attention since the intermolecular interactions induce an important excitonic effect (Frenkel exciton) combined with possible charge transfers and polaron pairs.…”

Section: Introductionmentioning

confidence: 99%

Intermolecular Interactions in Conjugated Oligothiophenes. 2. Quantum Chemical Calculations Performed on Crystalline Structures of Terthiophene and Substituted Terthiophenes

et al. 1999

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Quantum-chemical calculations are used to investigate the influence of intermolecular interactions on the absorption spectra of unsubstituted terthiophene (TT) as well as 3,3‘ ‘-dimethyl-2,2‘:5‘,2‘ ‘-terthiophene (DMTT) and 3‘,4‘-dibutyl-2,2‘:5‘,2‘ ‘-terthiophene (DBTT). The semiempirical ZINDO/S method is employed to calculate the energy of the electronic transitions of a single molecule in this crystalline structure and of interacting molecules in subcrystalline forms of various sizes (2 and 4 molecules). For all molecules investigated, intermolecular interactions lead to a splitting (Davydov's splitting) of the lowest optical singlet transition compared to that calculated for an isolated molecule. These results are interpreted through the use of the excitonic model. The splitting of the first electronic transition is very sensitive to the different intermolecular distances and orientations found in the crystalline structures of each molecule. TT shows an important excitonic effect on the first allowed transition whereas the splitting is less important for substituted terthiophenes. The spectral shifts caused by intermolecular interactions are compared with those induced by conformational changes toward planarity for the isolated molecules in the crystals (packing effects). The results clearly show that the excitonic effect is mainly responsible for the optical properties of TT in its aggregated form whereas, for substituted terthiophenes, the conformational change suggested in part 1 of this series of papers is the major cause of the red shifts observed in their absorption bands following aggregation.

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Section: Introductionmentioning

confidence: 99%

Intermolecular Interactions in Conjugated Oligothiophenes. 2. Quantum Chemical Calculations Performed on Crystalline Structures of Terthiophene and Substituted Terthiophenes

et al. 1999

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“…In many cases, the introduction of surface topographies via photolithography,6 the use of highly crystalline polymer and organic small‐molecule substrates to induce epitaxial growth,1, 7, 8 or the application of external fields, such as shear force4 and temperature gradient,9 can be employed to orient molecules unidirectionally in‐plane. Graphoepitaxy, for example, relies on surface topographies to induce long‐range orientation of molecules in organic thin films; this approach has been demonstrated to induce unidirectional in‐plane orientation over macroscopic distances in a wide variety of materials systems, including liquid crystals, block copolymers,6 and organic small molecules 10, 11. While orienting small molecules and polymers unidirectionally – or even biaxially – is seemingly straightforward today, prescribing crystallization along non‐linear shapes and patterns across a single substrate remains challenging.…”

mentioning

confidence: 99%

Guiding Crystallization around Bends and Sharp Corners

et al. 2012

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Control over the molecular orientation in organic thin films is demonstrated with precise in-plane spatial resolution over large areas. By exploiting the differential crystallization rates on substrates with different surface energies, the radial symmetry of spherulitic growth can be disrupted by preferentially selecting the molecular orientations that promote growth along the paths of the underlying patterns.

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“…This angle depends on the nature of the interfacial bond, the hybridization of the graft atom orbital, the chain length and the substrate. The orientation of dipolar molecules of SAMs formed on a particular surface can be evaluated by using Polarized Modulated Infrared Reflection Absorption Spectroscopy (PM-IRRAS) spectra and IR spectra of the isotopically dispersed molecules in a KBr pellet [22].…”

Section: Determination Of Orientation Of Thiol-based Sam Deposited On Cumentioning

confidence: 99%

Organic planar diode with Cu electrode via modification of the metal surface by SAM of fluorobiphenyl based thiol

Biswas¹,

Decorse²,

Kim³

et al. 2021

Applied Surface Science

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Spectroscopic Evidence for a Substrate Dependent Orientation of Sexithiophene Thin Films Deposited onto Oriented PTFE

Cited by 33 publications

References 44 publications

Intermolecular Interactions in Conjugated Oligothiophenes. 2. Quantum Chemical Calculations Performed on Crystalline Structures of Terthiophene and Substituted Terthiophenes

Intermolecular Interactions in Conjugated Oligothiophenes. 2. Quantum Chemical Calculations Performed on Crystalline Structures of Terthiophene and Substituted Terthiophenes

Guiding Crystallization around Bends and Sharp Corners

Organic planar diode with Cu electrode via modification of the metal surface by SAM of fluorobiphenyl based thiol

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