基于单层MoS2的柔性室温压电气体传感器构建及机理研究

Piezoelectric gas sensors can detect gas information at room temperature and realize self-powered without any external power sources through converting environmental mechanical energy into electrical sensing signals. Piezoelectric gas sensors show potential applications in emerging fields, such as Internet of Things, wearable technology, etc. In the previous works, our team worked on modifying nanostructure materials to improve the sensing performances, which was restrained by the nature of ZnO nanowires duo to their low specific surface area. On the other hand, monolayer MoS2 is a two-dimensional semiconductor integrating piezoelectric effect and gas sensing effect, which has large specific surface area and mounts of active sites for gas adsorption. Once the monolayer MoS2 was used as piezoelectric gas sensing materials, the sensor performances may be greatly improved. To develop two-dimensional piezoelectric gas sensors, it is the most important task to construct novel device structure and reveal the two-dimensional piezoelectric gas sensing mechanism. In this project, a flexible piezoelectric gas sensor based on monolayer MoS2 is constructed aiming at investigating the sensitization of two-dimensional materials during room-temperature piezoelectric gas sensing process. In addition, this project investigates the interaction between gas adsorption and charge carriers at the edge of monolayer MoS2, and the interaction between edge carriers and piezoelectric induced polarization electric field. This study may clarify the initial mechanism that edge adsorption process of gas molecules can modulate piezoelectric induced polarization electric field in monolayer MoS2, reveal the principle of piezoelectric-gas-sensing coupling effect and establish novel physical model called “two-dimensional piezoelectric gas sensing process”. This project provides scientific principle and application fundamental for the future researches of two-dimensional piezoelectric gas sensors.

压电气体传感器可在室温下检测气体，收集环境机械能转化为传感电信号，摆脱电源限制，在物联网、可穿戴等新兴领域具备潜在应用。申请人在前期工作中，修饰ZnO气敏材料以改善传感性能，但受限于一维纳米结构比表面积较低，性能提升有限。若以比表面积大、活性位多、同时具备压电效应和气体传感效应的单层MoS2作为压电气敏材料，或可大幅提升传感性能。构建新型器件结构，揭示二维压电气体传感机制，是研发二维压电气体传感器的首要任务。项目拟构建基于单层MoS2的柔性压电气体传感器，研究二维材料对室温压电气体传感过程的增敏作用；通过研究单层MoS2中气体分子吸附与边缘载流子的相互作用、边缘载流子与压电极化电场的相互作用，阐明边缘气体分子吸附对压电极化电场的调制过程，揭示单层MoS2中压电效应与气体传感效应耦合现象的物理本质，建立“二维压电气体传感过程”新物理模型。项目为二维压电气体传感器的研究提供科学依据和应用基础。

柔性压电传感器在室温气体传感领域具有广泛的应用前景。为进一步提高压电传感器的柔韧性和灵敏性，本项目将研发基于单层MoS2的柔性压电气体传感器。探索了多种单层MoS2的合成方式，发现化学气象沉积法制备的单层MoS2结晶面积大、单晶性好，符合项目需求。项目自制激光扫描共聚焦荧光/拉曼光谱仪用于高分辨率表征单层MoS2的缺陷、平整性，发现单层MoS2边缘处存在大量缺陷，有利用气体分子吸附，同时对单层MoS2的激子态布居进行深入讨论并提出双激子湮灭修正的半经典量子模型。通过PL光谱研究发现了单层MoS2的环境介电屏蔽效应，结合FDTD和FEM模拟揭示单层MoS2发光与环境介电常数的量化关系，并研制了荧光VOC蒸发传感器。将压电效应与介电屏蔽效应相结合，以单层MoS2和PET分别作为敏感材料和基底，通过湿法转移-光刻-镀膜法制备了气体传感器，具有良好的柔韧性，并对多种气体在室温下表现出优秀的灵敏性、响应恢复性及稳定性。对压电传感机理进行深入分析，揭示压电气体传感的本质是压电场受气体分子吸附调制的自由载流子屏蔽这一物理问题，并进一步归纳出“压电-载流子耦合效应”，将其拓展到压电场对激子的驱动作用。该项目对二维压电敏感材料的研究奠定了应用基础。