A definitive comprehension of morphology and photophysics in conjugated polymers at multiple length scales demands both single molecule spectroscopy and well-controlled molecular architectures.

In this manuscript, we report a design strategy to control polychromophore polymer folding at the single molecule level through hydrogen-bonding (H-bonding) interactions.

The synthesis and morphological investigation of a series of polychromophore polymers composed of oligomeric bis(2-ethylhexyl)-p-phenylenevinylene (BEH-PPV) (trimer, pentamer, and heptamer) monomers copolymerized with rigid morphological directing groups (morphons) are described. The polymerization was carried out using a Sonogashira cross-coupling polymerization between monomers composed of an iodo-terminated BEH-PPV oligomer and a bis(phenylacetylene)-containing morphon. The rigid morphons are prepared from adamantane and diamantane frameworks that are composed solely of sp 3 carbons, inhibit conjugation between BEH-PPV oligomers, and direct the local polymer morphology in either a bent or linear vector, respectively. The morphological properties of the polychromophore polymers were interrogated via single molecule fluorescence spectroscopy, thin-film absorption and fluorescence spectroscopy, and atomic force microscopy. Significant morphological variation was found upon substituting the morphon, as well as the chromophore size, with the most ordered structures being accessed with diamantane morphons.

Push–pull conjugated polymers have shown high performance in organic photovoltaic devices and yet, there have been fewer studies of the fundamental structure–property relationship in this class of materials compared to prototypical conjugated homopolymers MEH-PPV and P3HT.