Electrical and photoelectrical properties of polymer single nanowire made of diketopyrrolopyrrole-based conjugated copolymer bearing dithieno[3,2-b:2',3'-d]thiophene

摘要

We demonstrated a diketopyrrolopyrrole (DPP)-based alternating copolymer (i.e., PDTTDPP) which contains planar dithieno[3,2-b:2',3'-d]thiophene (DTT) unit and high effectiveness in the fabrication of solution-based polymer nanowires (PNWs). PDTTDPP was found highly crystalline and exhibited optimized energy levels for p-type semiconductor. The electrical properties of single PNWs such as specific resistivity (p) and photoresponsivity (R) were investigated by measuring the dark current and pho-tocurrent under visible and near-infrared lights. These electrical properties were compared for high (HA-PNW) and low (LA-PNW) aspect ratio PNWs produced using two different preparation methods such as membrane wetting method and self-assembly in a dilute solution. The measured responsivity (R) values of single HA-PNW at +40V are 134 and 114AW~(-1) at 632 and 830nm, respectively. In contrast, the R values of LA-PNW under identical conditions were determined to range from 0.55 AW~(-1) to 0.65AW~(-1) (A = 632nm) and from 0.61 AW~(-1) to 0.73AW~(-1) (A = 830nm) at a +40V bias voltage, which are significantly lower than those of HA-PNW-based devices.