The use of micrometer and nanometer‐sized organic single crystals to fabricate devices can retain all the advantages of single crystals, avoid the difficulties of growing large crystals, and provide a way to characterize organic semiconductors more efficiently. Moreover, the effective use of such “small” crystals will be beneficial to nanoelectronics. Here we review the recent progress of organic single‐crystalline transistors based on micro‐/nanometer‐sized structures, namely fabrication methods and related technical issues, device properties, and current challenges.

Sulfur dioxide (SO 2 ) is one of the most dangerous air pollutants that impair environment and human health. SO 2 in air is released during the burning of fossil fuels and plays one major role in the formation of acid rain. The repeated exposure to low levels of SO 2 can cause permanent pulmonary impairment for humans. [ 1 ] The long and short-term exposure limits for SO 2 gas are 2 and 5 ppm, respectively, [ 1 , 2 ] and the U. S. Environmental Control Agency has set the acceptable limit for SO 2 in ambient air at a level of 0.5 ppm. [ 3 ] It is of great importance to measure low concentration of SO 2 in air accurately and fast for human health protection and air-quality monitoring.Semiconductor resistor sensors are, for more than 30 years, one of the most common used gas sensors to detect toxic and fl ammable gases such as NO 2 , H 2 S, CO, NH 3 , and H 2 because of their distinguished merits such as low cost, long lasting, high sensitivity, and good reliability, etc. [ 4 ] Organic fi eld-effect transistor (OFET) is another alternative semiconductor sensing technology with advantages over resistors, and has attracted much attention only recently. [ 5 ] The sensitivity can be dramatically enhanced by changing the source-drain current ( I SD ) of OFET when operating the sensors in the sub-threshold regime, as a result of the current modulation by the extra gate electrode. [ 6 ] Another advantage of OFET sensors is that the sensing response can be enhanced by integrating them in oscillator and adaptive amplifi er circuits. [ 7 ] These advantages combined with low cost and light weight of organic semiconductors ensure that OFET sensors have attracted much attention for the detection of a wide range of gases. [ 8 ] However, only few efforts have been made to develop the semiconductor SO 2 sensors and almost all of them are resistortype (a detailed performance list for the reported semiconductor SO 2 sensors is shown in Supporting Information Table S1). The semiconductor materials are mainly focused on metal oxide, such as SnO 2 , WO 3 and TiO 2 . Most reported semiconductor SO 2 sensors require an operating temperature of 200-600 ° C, demonstrate a sensitivity lower than 50%, face challenges in low concentration detection, or suffer from a slow response and recovery time of over 10 min.In this communication, an OFET based on gas dielectric and CuPc single crystalline nanowire as a novel SO 2 sensor with complete recovery and room-temperature detection is reported.To the best of our knowledge, this is the fi rst demonstration of SO 2 gas sensing based on OFETs. The sensitivity is characterized by the enhanced fi eld-effect mobility and is as high as 764% in 20 ppm SO 2 . The detect limitation is down to sub-ppm levels (0.5 ppm) with high sensitivity (119%) and high resolution (100 ppb). The exposed conductive channel is shown to be responsible for the sensitivity to SO 2 . Figure 1 a shows a schematic image of the gas dielectric fi eldeffect transistor (FET) sensor based on CuPc nanowire and the adsorption of SO 2 ...

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