Facile Monitoring of Fullerene Crystallization in Polymer Solar Cell Blends by UV-vis Spectroscopy.

Camilla Lindqvist, Ergang Wang, Mats R. Andersson, Christian Muller

    Research output: Contribution to journalArticlepeer-review

    16 Citations (Scopus)

    Abstract

    A simple technique is demonstrated based on UV-vis spectroscopy that permits the onset of fullerene crystallization to be monitored in polymer:fullerene bulk-heterojunction blends. The growth of fullerene crystals only occurs during thermal annealing above the glass transition temperature (Tg) of the blend. Light scattering due to the presence of micrometer-sized fullerene crystals reduces the apparent transmittance, which can serve as a clear indicator for the upper limit of the Tg. This principle is used to deduce this critical parameter for two high-performance photovoltaic blends that are based on a thiophene-quinoxaline and a thiophene-isoindigo copolymer, respectively. High Tgs of 115 and 145 °C promise good thermal stability. UV-vis spectroscopy is used to monitor the onset of fullerene crystallization in polymer:fullerene bulk-heterojunction blends. Micrometer-sized fullerene crystals grow during thermal annealing and scatter light, which can serve as a clear indicator for the upper limit of the glass-transition temperature of the blend.

    Original languageEnglish
    Pages (from-to)530-535
    Number of pages6
    JournalMacromolecular Chemistry and Physics
    Volume215
    Issue number6
    DOIs
    Publication statusPublished - Mar 2014

    Keywords

    • bulk heterojunctions
    • crystal growth
    • glass transition temperature
    • organic photovoltaics
    • UV-vis spectroscopy

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