Tuning Surface Energy of Conjugated Polymers via Fluorine Substitution of Side Alkyl Chains: Influence on Phase Separation of Thin Films and Performance of Polymer Solar Cells.

ABSTRACT: Different contents of fluorine in side alkyl chains were incorporated into three conjugated polymers (namely, PBDTTT-f13, PBDTTT-f9, and PBDTTT-f5) whose backbones consist of benzodithiophene donors and thienothiophene acceptors. These three fluorinated polymers, in comparison with the well-known analogue PTB7-Th, show comparable energy levels and optical band gaps. However, the fluorination of side alkyl chains significantly changed the surface energy of bulk materials, which leads to distinctly different self-assembly behaviors and phase separations as being mixed with PC₇₁BM. The increased mismatch in surface energies between the polymer and PC₇₁BM causes larger scale phase domains, which makes a sound explanation for the difference in their photovoltaic properties.

SUBMITTER: Liu Y 

PROVIDER: S-EPMC6641192 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature