Nanoscale Chain Alignment and Morphology in All-Polymer Blends Visualized Using 2D Polarization Fluorescence Imaging: Correlation to Power Conversion Efficiencies in Solar Cells

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Abstract

All-polymer blends are promising materials for organic electronics. Their performance critically depends on the quality of mixing of the electron donor and acceptor polymers and on the local chain organization. We investigated spatially resolved photoluminescence properties of as-prepared and annealed blends of poly[2,3-bis(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) and poly(N,N-bis-2-octyldodecyl-naphtalene-1,4,5,8-bisdicarboximide-2,6-diyl-alt-5,5-2,2-bithiophene) (N2200) using two-dimensional polarization imaging (2D POLIM). N2200 is known to aggregate into fiber-like morphologies with a few hundreds of nanometers lateral extensions. Our findings suggest a highly parallel chain organization within individual domains. Comparing blends differing in the batch of the N2200 component, we could relate decreased power conversion efficiencies of the corresponding devices to aggregation of N2200 in tens of micrometer-sized elongated structures. TQ1 showed less sensitivity to preparation conditions. Other than N2200, TQ1 is liquid crystalline, and its side chain structure hinders aggregation. It thus might be feasible to consider similar properties for the design of acceptor polymers as well.

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  • Linköping University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Polymer Chemistry
Original languageEnglish
Pages (from-to)21848-21856
Number of pages9
JournalJournal of Physical Chemistry C
Volume121
Issue number40
StatePublished - 2017 Oct 12
Peer-reviewedYes