Gas Sensors Based on Nano/Microstructured Organic Field‐Effect Transistors

Abstract

Benefiting from the advantages of organic field‐effect transistors (OFETs), including synthetic versatility of organic molecular design and environmental sensitivity, gas sensors based on OFETs have drawn much attention in recent years. Potential applications focus on the detection of specific gas species such as explosive, toxic gases, or volatile organic compounds (VOCs) that play vital roles in environmental monitoring, industrial manufacturing, smart health care, food security, and national defense. To achieve high sensitivity, selectivity, and ambient stability with rapid response and recovery speed, the regulation and adjustment of the nano/microstructure of the organic semiconductor (OSC) layer has proven to be an effective strategy. Here, the progress of OFET gas sensors with nano/microstructure is selectively presented. Devices based on OSC films one dimensional (1D) single crystal nanowires, nanorods, and nanofibers are introduced. Then, devices based on two dimensional (2D) and ultrathin OSC films, fabricated by methods such as thermal evaporation, dip‐coating, spin‐coating, and solution‐shearing methods are presented, followed by an introduction of porous OFET sensors. Additionally, the applications of nanostructured receptors in OFET sensors are given. Finally, an outlook in view of the current research state is presented and eight further challenges for gas sensors based on OFETs are suggested.

Monolayer Two‐dimensional Molecular Crystals for an Ultrasensitive OFET‐based Chemical Sensor

“…However, the sensing performances of thin film OFET‐based sensors are limited by the diffusion process of analyte molecules to the conducting channels . To improve the sensing performances, many efforts have been devoted to alleviate the diffusion barrier by either introducing porous structure into organic semiconductor (OSC) films or decreasing the film thickness down to a few layers or even monolayers …”

“…Further improvement over the detection limit (that is, ca. 10 ppb) was achieved by decreasing the thickness of semiconductor layer to few molecular layers, for example, monolayer films and monolayer molecular crystals (MMCs) . On the other hand, introducing porous structure was also shown to be an alternative strategy to tailor the sensitivity, which have enabled the NH 3 detection limit of 1–10 ppb .…”

Organic Heterojunction Devices Based on Phthalocyanines: A New Approach to Gas Chemosensing

“…There are mainly two device structures studied so far, incorporating MPc-based heterostructures for chemosensing application; which are OFET and MSDI. The former offers a much broader range of device configuration designs, as highlighted in recent reviews devoted to OFET-based gas sensors [ 12 , 59 , 60 ]. Among different OFET designs employing organic heterostructures, the two most commonly used ones are the suspended-gate and top-gate configurations shown in Figure 6 a,b, which are distinguished by the relative position of dielectric and gate components in the device.…”

CO2 and O2 Detection by Electric Field Sensors

“…The detection and the measurement of gas concentrations can be carried out using several principles. The most common working principles, sensors, and systems used for gas detection are: electrochemical sensors [1,2], systems based on Quartz Crystal Microbalances [3], sensors based on semiconductors [4,5], optical sensors [6], capacitive sensors [7], cantilever-based sensors [8], and colorimetric devices [9].…”

“…It is ambitious to propose a gas sensor which is completely novel (especially for the detection of oxygen and carbon dioxide) with sensitivity, resolution, selectivity, and repeatability better than the ones given by the existing technologies (reported in References [1][2][3][4][5][6][7][8][9][10]). All the mentioned sensors (not pretending to be exhaustive) are complementary in terms of pros and cons, and the best solution can be selected among them for each different application.…”