Degradation mechanism of benzodithiophene-based conjugated polymers when exposed to light in air

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DOIResolve DOI: http://doi.org/10.1021/am300362b
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TypeArticle
Journal titleACS Applied Materials & Interfaces
ISSN1944-8244
1944-8252
Volume4
Issue6
Pages29932998; # of pages: 6
Subjectbenzodithiophene; low band gap polymers; solar cell; bulk heterojunction; photostability
AbstractWe report the investigation of the air photostability of benzo[1,2-b:4,5-b′]dithiophene (BDT) based conjugated polymers using UV–visible spectroscopy, X-ray photoelectron spectroscopy, gel permeation chromatography, and nuclear magnetic resonance spectroscopy. Three low band gap alternating D–A copolymers consisting of 3-fluoro-2-heptylcarbonylthieno[3,4-b]thiophene and alkyl-substituted BDT, alkoxy-substituted BDT, or dithienosilole, respectively, were prepared for investigating their photovoltaic performance and photostability. After only two hours of simultaneous exposure to light and air, the main absorption peak of the polymer films containing BDT units blue-shifted and its intensity dramatically decreased. We demonstrated that the BDT unit underwent dramatic structural change under illumination in air by reacting with the oxygen molecules at the excited state, leading to the disruption of the main-chain conjugation of the polymer. As a result, the color of the alkyl-BDT based polymer film permanently changed from deep blue to light yellow. In contrast, the dithienosilole based polymer was quite stable when treated under the same condition with negligible change in the absorption spectrum.
Publication date
LanguageEnglish
AffiliationInformation and Communication Technologies; Energy, Mining and Environment; Security and Disruptive Technologies; National Research Council Canada
Peer reviewedYes
NPARC number21268861
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Record identifier69dbfb5b-edb1-422c-a274-e32599eb8ea2
Record created2013-11-15
Record modified2016-05-09
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