Spectral multitude and spectral dynamics reflect changing conjugation length in single molecules of oligophenylenevinylenes

Kobayashi, Hiroyuki; Tsuchiya, Kousuke; Oginö, Kazuhíde; Vácha, Martin

doi:10.1039/c2cp41509g

Cited by 19 publications

(29 citation statements)

References 38 publications

(51 reference statements)

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“…1B, asterisks) or do not emit at all. In contrast, for PDOPT16 with only a single emitting site, the ZPL distribution is entirely determined by dispersive interactions of the emitting site with the local environment (42,43) as well as by the degree of planarity of the polymer backbone, both of which vary for each chain (43)(44)(45).…”

Section: Significancementioning

confidence: 97%

Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes

Raithel

Simine

Pickel

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The backbone conformation of conjugated polymers affects, to a large extent, their optical and electronic properties. The usually flexible substituents provide solubility and influence the packing behavior of conjugated polymers in films or in bad solvents. However, the role of the side chains in determining and potentially controlling the backbone conformation, and thus the optical and electronic properties on the single polymer level, is currently under debate. Here, we investigate directly the impact of the side chains by studying the bulky-substituted poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) and the common poly(3-hexylthiophene) (P3HT), both with a defined molecular weight and high regioregularity, using low-temperature single-chain photoluminescence (PL) spectroscopy and quantum-classical simulations. Surprisingly, the optical transition energy of PDOPT is significantly (∼2,000 cm or 0.25 eV) red-shifted relative to P3HT despite a higher static and dynamic disorder in the former. We ascribe this red shift to a side-chain induced backbone planarization in PDOPT, supported by temperature-dependent ensemble PL spectroscopy. Our atomistic simulations reveal that the bulkier 2,5-dioctylphenyl side chains of PDOPT adopt a clear secondary helical structural motif and thus protect conjugation, i.e., enforce backbone planarity, whereas, for P3HT, this is not the case. These different degrees of planarity in both thiophenes do not result in different conjugation lengths, which we found to be similar. It is rather the stronger electronic coupling between the repeating units in the more planar PDOPT which gives rise to the observed spectral red shift as well as to a reduced calculated electron-hole polarization.

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Section: Significancementioning

confidence: 97%

Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes

Raithel

Simine

Pickel

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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“…Thereby, localization of π-electrons over a multitude of distances due to defects is translated into a multitude of absorption and PL responses [107]. More information on the methods used to control structure and morphology from the molecular to the macroscopic level and how chain conformation influences the resulting optoelectronic and photophysical properties of active layers of conjugated polymers can be found in the literature in several well documented reviews [108–111].…”

Section: Influence Of Molecular Conformations and Long-range Arrangemmentioning

confidence: 99%

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

Botiz

Stingelin

2014

Materials

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It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties.

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“…All-transb-carotene as an ideal molecule plays an important role in investigating the p-electron conjugated properties of the shortchain polymer molecule. Numerous studies have been carried out to characterize the physical properties of polyenes through several models, such as the coherent weakly damped electron-lattice vibration model [8], effective conjugation length model [9,10], effective conjugation coordinate model [11], and amplitude model [12,13]. In many studies, the resonance Raman scattering spectroscopy is often applied to investigate the structural characteristics of the molecule, which is one of the most useful methods to identify the phonon modes coupled to an electronic system [14].…”

Section: Introductionmentioning

confidence: 99%

The electron–phonon coupling of fundamental, overtone, and combination modes and its effects on the resonance Raman spectra

Wang

et al. 2015

Materials Research Bulletin

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Spectral multitude and spectral dynamics reflect changing conjugation length in single molecules of oligophenylenevinylenes

Cited by 19 publications

References 38 publications

Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes

Direct observation of backbone planarization via side-chain alignment in single bulky-substituted polythiophenes

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

The electron–phonon coupling of fundamental, overtone, and combination modes and its effects on the resonance Raman spectra

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