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Thin films of a series of symmetrical 2,5-bis(dodecanoxy)phenyleneethynylenes, bearing a butadiyne central group and 4, 6 and 8 phenyleneethynylene moieties, were prepared by spin coating. In general, narrower and red shifted peaks are observed in both absorption and emission spectra with respect to the solutions previously reported, however, the fluorescence quantum yield was quenched. All of these features are explained with the planarization of the conjugated chain, and intra/intermolecular interactions, as supported by spectroscopic aggregation studies and by atomic STM and microscopic AFM characterization. By cathodoluminescence spectroscopy, hot charged states are found that may also affect the fluorescence and electroluminescence properties. From the series, the latter were studied for the hexamer 6DAc for which an oLED with configuration ITO/PEDOT:PSS/6DAc/Al was constructed in ambient conditions, giving a threshold voltage of 11 V and quantum yield of 0.031 ph/e%, of the same order of other phenyleneethynylenes or phenylenebutadyines devices.

Polydiacetylenes (PDAs) self-assembled onto silver nanoparticles (AgNPs) show superior performance relative to conventionally-structured PDAs because their unique optical properties are combined with the peculiar features of the nanosized noble metal cores. The present paper presents a study of the experimental factors influencing the photopolymerization of the carboxy-terminated 10,12-pentacosadiynoic acid (PCDA) monomer anchored to silver nanoparticles in an aqueous solution. Specific spectroscopic parameters have been identified that characterize the process both qualitatively and quantitatively, thus allowing the comparison of the polymerization yield carried out under different experimental conditions. On this basis, a well-defined synthetic protocol able to maximize the chromophoric potential of these novel optical transducers, as well as to give reproducible results, is proposed and tested on differently-stabilized and/or aged silver nanoparticles used as substrates for the PCDA chemisorption. The highly-conjugated blue polyPCDA has considerable potential in the optoelectronic, photovoltaic and sensing fields.