2D Material Based PTE Detectors with Room Temperature Operations

Abstract

Real-time, room-temperature operation and self-powered photothermoelectric (PTE) detection emeries are advanced and versatile solutions for various applications. These detectors offer the advantage of not requiring external power sources, making them portable and suitable for remote or low-power environments. Additionally, their ability to operate at room temperature eliminates the need for costly and complex cooling systems, making them more accessible and cost-effective for various industries and research fields. However, issues of massive fabrication, complicated manipulations, long-term stability, and flexibility are concerned with engaging new exploration on PTE detectors with low-dimensional materials. Two-dimensional (2D) materials are emerging as leading ones due to their broadband detection from Terahertz (THz) to ultraviolet (UV), electrical conductivity with a small band gap, and strong polymer affinity for thermoelectrical conversion. This thesis aims at using 2D nanomaterials of graphene and molybdenum carbide (Mo₂C) MXene for exploring new PTE detectors, guiding 2D materials methodology, leading the investigation of polymer composites, and providing insights into various industrial, imaging, and health monitor applications. This thesis introduces three types of room operation and self-powered PTE architectures with 2D nanomaterials. First, we developed a new doped polyaniline (PANI) as the composite material with a few layers of sheets of graphene. Semi-transparent, broadband infrared (IR) detection and robust flexibility features are presented. Second, a vertical graphene/polyethylenimine (PEI) composite multi-element H-shaped detector with the spray-coating method is presented. High response time, detectivity, and a broadly responsive range are achieved with PEI concentration adjustment, lowering the thermal conductivity and enhancing compacity, focusing the realistic situations with low incident power. Finally, we propose a low-noise PTE device that operates at room temperature by Mo₂C and Poly(3,4-ethylene-dioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) nanomaterials with a flexible PET substrate. Superior energy conversion and long-term stability of the material and sustainability from surroundings are achieved through material optimizations. Based on such PTE detectors, two promising systems—the motion tracking system and the non-destructive testing (NDT) imaging system—demonstrate the time-tracking of human radiation and high-resolution imaging applications.