Regioregular A1-D-A2-D acceptor polymers with thienopyrroledione (TPD) or diketopyrrolopyrrole (DPP) as electron-withdrawing unit for high performance all-polymer photodetectors

All-polymer photovoltaic devices have been rapidly developed in recent years for their unique features and promising application values. Although common donor-acceptor (D-A) polymer acceptors were synthesized and utilized, it is still urgent to study new structures of polymer acceptors to meet various donor materials, and in turn optimize the performances of devices. Herein, we presented two acceptor-1-donor-acceptor-2-donor (A1-D A2-D) conjugated polymers, namely as P(NDI-T-TPD) and P(NDI-T-DPP) based on naphthalenediimide (NDI) and two different electron-withdrawing units thienopyrroledione (TPD) or diketopyrrolopyrrole (DPP), respectively. Compared with P(NDI-T-DPP), P(NDI-T-TPD) formed more planar molecular conformation and evident face-on orientation. By pairing with three typical polymer donors J71, PM6, and PTB7-Th, the crystallinity, morphology, and carrier transfer behaviors of blend films were finely improved. As a result, the UV-vis-NIR all-polymer photodetector based on PTB7-Th:P(NDI-T-TPD) exhibited maximum responsivity of 222.7 mA/W and specific detectivity of 2.6 x 1013 cm Hz1/2/W at-0.1 V. In addition to the device possessed fast response speed (& tau;r/& tau;f = 5.2/38.5 & mu;s) and a large LDR of 110.1 dB. Most importantly, the photodetector also showed extraordinary air stability for 1000 h. This work indicates that high-performance all-polymer photodetectors with optimal morphology and stability can be realized via designing regioregular A1-D-A2-D acceptor polymers with a finetuned A2 unit.