Tuning optical properties and enhancing solid-state emission of poly(thiophene)s by molecular control: a postfunctionalization approach

Li, Yuning, Vamvounis, George, and Holdcroft, Steven (2002) Tuning optical properties and enhancing solid-state emission of poly(thiophene)s by molecular control: a postfunctionalization approach. Macromolecules, 35 (18). pp. 6900-6906.

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Abstract

Postfunctionalization of poly(3-hexylthiophene) (P3HT) enables the systematic study of electronic and steric effects of various functional groups on the optical and photophysical properties of 3,4-disubstituted poly(thiophene)s. In solution, these 3,4-disubstituted poly(thiophene)s exhibit a lower fluorescence yield (Phi(fl)) than P3HT. In the solid state, bromo, chloro, and formyl groups increase Phi(fl), whereas nitro groups completely quench fluorescence. Phenyl, p-tolyl, 2- and 4-methoxyphenyl, 2-thienyl, biphenyl, and 1-naphthyl substituents increase the solid-state fluorescence of P3HT by a factor of 2-3 as a result of steric interactions that force the aromatic substituents perpendicular to the main chain. An extensive enhancement in the solid-state Phi(fl), 12 times greater than that of P3HT, is observed for polymers containing ortho-alkylphenyl or 2-(3-alkyl)thienyl groups, because of additional steric interactions between methyl or alpha-methylene hydrogens on the phenyl or thienyl substituents and main-chain thienyl groups. These interactions further increase the planarity of the polymer backbone and lead to an enlargement of the interplanar distance. Partial substitution of P3HT with o-tolyl groups affords polymer films with a solid-state Phi(fl) of up to 22%.

Item ID: 32713
Item Type: Article (Research - C1)
ISSN: 1520-5835
Funders: Natural Sciences and Engineering Research Council of Canada
Date Deposited: 24 Feb 2016 02:41
FoR Codes: 03 CHEMICAL SCIENCES > 0305 Organic Chemistry > 030505 Physical Organic Chemistry @ 100%
SEO Codes: 85 ENERGY > 8505 Renewable Energy > 850504 Solar-Photovoltaic Energy @ 100%
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