Carbon nanotube-based, serially connected terahertz sensor with enhanced thermal and optical efficiencies

Abstract

Owing to their high thermal and optical performances, carbon nanotube (CNT) films are used in various photo-thermo-electric (PTE) applications, such as terahertz (THz) sensing and energy harvesting. To improve the performance of PTE devices, a device structure should be designed based on a deep understanding of the thermal and optical responses of the CNT film. However, the optical properties of CNT films in the THz frequency region remain unclear because of the difficulties associated with device processing and measurements. Herein, we report our findings on the thermal and optical characteristics of CNT films. The shape of the CNT film that maximizes the product of the thermal and optical factors (optimal structure of the PTE sensor) depends on the frequency of the irradiating electromagnetic wave. The optimal film thickness and width values for THz irradiation range from 300–600 nm and 50–70 µm, respectively. Subsequently, we fabricated a serially connected, multi-element PTE sensor with an optimal device structure and enhanced the detection sensitivity by approximately 13 times compared with a single-element PTE sensor. In addition, we demonstrated the first THz spectroscopy application using a PTE sensor. The findings of this study, thermal/optical factor enhancement, and micro-sized CNT film processing technology can be used to improve the performance of all CNT-based photothermal devices, including PTE sensors and thermoelectric generators.

All‐Screen‐Coatable Photo‐Thermoelectric Imagers for Physical and Thermal Durability Enhancement

“…The conventional device design process involves self-aligned selective suction filtration of the CNT solution (Figure 3a,b), adhesive transfer from a membrane substrate to a tape (Figure 3c), and moves on to subsequent steps such as laser cutting or attachment to other functional substrates or 3D structures. [19,20,[25][26][27] "Carbon nanotubes" in the Experimental Section describe the details of these processes. This work focused on the behavior at the CNT film channel-readout electrode interface.…”

Outstanding Robust Photo- and Thermo-Electric Applications with Stabilized n-Doped Carbon Nanotubes by Parylene Coating

“…Furthermore, although the features of these dopants, which are soluble in water and alcohol, make it easy to fabricate devices, they have the disadvantage of impeding the wearable and outdoor use of CNT devices. Previously, we reported CNT-based NIR–THz sensors and related photo-thermo-electric sensing applications. ,,,− However, the air stability of the sensor has not been discussed thus far. In fact, our sensor malfunctioned after operating for several months under air conditions.…”

System design of large-area vertical photothermoelectric detectors based on carbon nanotube forests with MXene electrodes

“…As the most comprehensively studied PTE materials, types of CNTs show ordered growth control, facile synthesis methods, and excellent PTE properties. 23–26…”

“…As the most comprehensively studied PTE materials, types of CNTs show ordered growth control, facile synthesis methods, and excellent PTE properties. [23][24][25][26] However, there are some other challenges with current PTE detectors. First, current vertical PTE detectors mainly use metals as top electrodes.…”