Abstract
A thin-film transistor (TFT) having an organic–inorganic hybrid thin film combines the advantage of TFT sensors and the enhanced sensing performance of hybrid materials. In this work, poly(3-hexylthiophene) (P3HT)-zinc oxide (ZnO) nanoparticles' hybrid thin film was fabricated by a spraying process as the active layer of TFT for the employment of a room temperature operated formaldehyde (HCHO) gas sensor. The effects of ZnO nanoparticles on morphological and compositional features, electronic and HCHO-sensing properties of P3HT-ZnO thin film were systematically investigated. The results showed that P3HT-ZnO hybrid thin film sensor exhibited considerable improvement of sensing response (more than two times) and reversibility compared to the pristine P3HT film sensor. An accumulation p-n heterojunction mechanism model was developed to understand the mechanism of enhanced sensing properties by incorporation of ZnO nanoparticles. X-ray photoelectron spectroscope (XPS) and atomic force microscopy (AFM) characterizations were used to investigate the stability of the sensor in-depth, which reveals the performance deterioration was due to the changes of element composition and the chemical state of hybrid thin film surface induced by light and oxygen. Our study demonstrated that P3HT-ZnO hybrid thin film TFT sensor is beneficial in the advancement of novel room temperature HCHO sensing technology.
Highlights
Formaldehyde (HCHO) is a colorless volatile organic compound (VOC) with a strong, pungent-smelling that can be toxic, allergenic and carcinogenic [1]
Considerable efforts have been devoted to the development of different types of HCHO gas sensors, including resistive sensors composed of metal oxide semiconductor [6] and carbon nanotubes [7,8], quartz crystal microbalance (QCM) sensors [9], organic thin-film transistor (OTFT) sensors [10] and fiber-optic biochemical sensors [11]
HCHO sensing properties with higher response value and better reversibility were obtained compared to pristine P3HT thin film sensor, which was attributed to three-dimensional porous morphology and accumulation p-n heterojunction structure of P3HT-zinc oxide (ZnO) hybrid thin film
Summary
Formaldehyde (HCHO) is a colorless volatile organic compound (VOC) with a strong, pungent-smelling that can be toxic, allergenic and carcinogenic [1]. Considering its widespread use, toxicity and volatility, exposure to HCHO is a significant consideration for human health. Developing portable, cheaper and resumable HCHO gas sensors operated at room temperature is in urgent need in both industrial and residential environments. Considerable efforts have been devoted to the development of different types of HCHO gas sensors, including resistive sensors composed of metal oxide semiconductor [6] and carbon nanotubes [7,8], quartz crystal microbalance (QCM) sensors [9], organic thin-film transistor (OTFT) sensors [10] and fiber-optic biochemical sensors [11]. OTFT has been shown to be an inexpensive, portable and disposable diagnostic device because of its low cost, ease of fabrication and solution processibility, which are favorable for gas sensor application [12,13]
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