Post-Polymerization C-H Borylation of Donor-Acceptor Materials Gives Highly Efficient Solid State Near-Infrared Emitters for NIR-OLEDs and Effective Biological Imaging

Daniel Crossley, Laura Urbano, Robert Neumann, Struan Bourke, Jennifer Jones, Lea Ann Dailey, Mark Green, Martin J. Humphries, Simon M. King, Michael Turner, Michael Ingleson

    Research output: Contribution to journalArticlepeer-review

    37 Downloads (Pure)

    Abstract

    Post-polymerization modification of the donor–acceptor polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole), PF8-BT, by electrophilic C–H borylation is a simple method to introduce controllable quantities of near-infrared (near-IR) emitting chromophore units into the backbone of a conjugated polymer. The highly stable borylated unit possesses a significantly lower LUMO energy than the pristine polymer resulting in a reduction in the band gap of the polymer by up to 0.63 eV and a red shift in emission of more than 150 nm. Extensively borylated polymers absorb strongly in the deep red/near-IR and are highly emissive in the near-IR region of the spectrum in solution and solid state. Photoluminescence quantum yield (PLQY) values are extremely high in the solid state for materials with emission maxima ≥ 700 nm with PLQY values of 44% at 700 nm and 11% at 757 nm for PF8-BT with different borylation levels. This high brightness enables efficient solution processed near-IR emitting OLEDs to be fabricated and highly emissive borylated polymer loaded conjugated polymer nanoparticles (CPNPs) to be prepared. The latter are bright, photostable, low toxicity bioimaging agents that in phantom mouse studies show higher signal to background ratios for emission at 820 nm than the ubiquitous near-IR emissive bioimaging agent indocyanine green. This methodology represents a general approach for the post-polymerization functionalization of donor–acceptor polymers to reduce the band gap as confirmed by the C–H borylation of poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2c,2cc-diyl) (PF8TBT) resulting in a red shift in emission of >150 nm, thereby shifting the emission maximum to 810 nm.
    Original languageEnglish
    JournalACS Applied Materials and Interfaces
    Early online date7 Aug 2017
    DOIs
    Publication statusPublished - 2017

    Keywords

    • near-infrared emission
    • bioimaging
    • post-polymerization modification
    • C-H borylation
    • low band-gap

    Fingerprint

    Dive into the research topics of 'Post-Polymerization C-H Borylation of Donor-Acceptor Materials Gives Highly Efficient Solid State Near-Infrared Emitters for NIR-OLEDs and Effective Biological Imaging'. Together they form a unique fingerprint.

    Cite this