Doped Polyaniline/Graphene Composites for Photothermoelectric Detectors

The development of photothermoelectric (PTE) detectors has drawn much attention and is a hot research topic because of their superiority of converting broadband terahertz to mid-infrared radiation energy without any bias support in ambient conditions. However, earlier work in PTE detectors is complicated by a sophisticated fabrication process, uncontrollable formation, poor flexibility, and intractable material instability. Herein, we apply doped polyaniline (PANI)/graphene composites on poly(ethylene terephthalate) substrates to propose a new type of PTE detectors. The facile fabrication process, involving tip sonification and magnetic stirring, enhances the dispersion of homogeneously aqueous graphene. Besides the uniformity of the composite, the bias-free photodetector exhibits its highly sensitive responsivity by tuning the graphene concentration, achieving a peak detectivity of 6.8 × 107 cm Hz1/2 W–1 and responsivity of 2.5 V W–1. In addition, various bending radii (−1.5 to 1.5 cm) and more than 300 multiple bending cycles demonstrate remarkable flexibility of the doped-PANI/graphene composite. We further simulate human interactions by setting fingers 3–5 mm away from detectors and moving fingertips along the perpendicular direction toward the detector in multiple attempts to exhibit a rapid, high-performance photovoltage response of 10 μV. Overall, the striking doped-PANI/graphene composite PTE detectors manifest satisfactory broadband detectivity and provide insights into abundant applications in nondestructive health monitors, future optical detectors, and wearable Internet of Things (IoT) devices.