Low-bandgap donor–acceptor polymers for photodetectors with photoresponsivity from 300 nm to 1600 nm

A novel donor unit dithienobenzotrithiophen (DTBTT) was designed and utilized in the synthesis of a series of donor–acceptor (D–A) polymers with the thienoisoindigo-based acceptor. The relationships between the structure of polymers and the absorption spectra, electrochemistry properties, hole mobility, and photovoltaic properties of these polymers have been studied. The results showed that low-bandgap D–A polymers containing DTBTT are suitable for use in broadband polymer photodetectors. Polymer photodetectors exhibited a specific detectivity (D*) in the order of 1012 Jones, low dark current and photoresponsivity at the wavelengths from 300 to 1600 nm.