Synthesis of a dithieno[3,2-b:2′,3′-d]silole-based conjugated polymer and characterization of its short wave near-infrared fluorescence properties

Short wave near-infrared (SWIR, 900–1700[Formula: see text]nm) fluorescence imaging has attracted extensive research interest from scientists due to its high imaging quality. However, the variety of SWIR fluorescence imaging agents are quite limited and the corresponding quantum efficiency is relatively low. In this work, a novel conjugated polymer PDTSDTBT was reported, consisting of a donor unit with a tetrahedral Si (sp3) named DTS and an acceptor unit named DTBT with branched side chains. The design approach of endowing the donor–acceptor structure with the branched side chains successfully increase the fluorescence quantum efficiency. The polymer was prepared into nanoparticles by nanoprecipitation. The PDTSDTBT nanoparticles showed an absorption peak of 626[Formula: see text]nm and fluorescence emission peak of 924[Formula: see text]nm. The quantum efficiency of the nanoparticles is 0.53%, which is higher than that of nanotube fluorophores (0.4%). The nanoparticles also demonstrate a photothermal effect, the temperature of nanoparticles solution could reach [Formula: see text]C under excitation by 660[Formula: see text]nm laser. Therefore, the PDTSDTBT nanoparticles is an excellent fluorescent imaging agent with potential photothermal applications.