Significantly Boosted Photothermoelectric Effect via Carrier Injection in Au Decorated SWCNT Films for Infrared Detection

Carbon nanotubes (CNTs) have established their promising application as infrared photodetector and the photothermoelectric (PTE) effect is demonstrated to play a critical role. While extensive studies are focused on the optoelectronic behaviors, the thermoelectric conversion involved in the PTE has been pursued to less extent probably due to the overall low thermopower under infrared (IR) illumination. Herein, to trigger a stronger PTE response, Au/CNT heterojunctions are formed by Au nanoparticles (NPs) decoration of CNT films to facilitate both light absorption and carrier transportation, so that thermoelectric property is enhanced simultaneously. Significant boost on infrared radiation energy conversion capability is therefore enabled in Au NPs decorated CNT film, delivering maximum output voltage of 26.1 mV and power of 27.3 µW, outperforming the state-of-the art photodetectors based on PTE effect. The transport mechanism is revealed via combining in situ Kelvin Probe Force Microscope mapping of the surface potential and macroscopic transport and output performances under IR illumination. Finally, the IR detection function is validated via an 8-channel IR detector prototype, presenting sensitive responsivity and long-term cyclic stability. The study thus demonstrates the PTE effect as a promising platform toward high-performance optoelectronic applications such as IR detection and solar energy harvesting.