The Effect Of Gas Dielectric And Ph5T2-modified On Gas Sensing Performance Of Micrometer And Nanometer-sized CuPc Single Crystal Field-effect Transistor

Organic filed-effect gas sensor has attracted lots of attention due to the advantages of flexibility,light mass,low operating temperature,signal amplification,multi-parameter,etc.However,a few major challenges still need to be solved urgently,in particular,sensitivity,selectivity,stability and repeatability.To effectively improve the gas sensing performances,some methods have been applied,which include new type device configuration,surface modification,using one-dimensional nanomaterials as a semiconductor,etc.Among them,fabricating the devices with air dielectric will be an effective method which exposes conducting channel,the most sensitive part,to the tested gas in order to enhance the sensing performances.In addition,constructing heterojunction by surface modification is also a resultfulmethod to improve response ability and realizetheselectivity.In consideration of the above two points,we fabricated CuPc micro/nano crystal field-effect transistor with air dielectric and obtained the gas sensor with good stability,high responsibility and selectivity via surface modification.The main contents are as follows:1.We fabricated the CuPc micro/nano crystal field-effect transistor on the air dielectric by mechanical transfer.Multi-measuredtransfer curves of the transistor are well overlapped,which shows the excellent repeatability and stability of the device.The results ensure the following experiments more reliable.2.The gas sensing tests were carried out based on CuPc micro/nano crystal field-effect transistor with air dielectric.During the tests,we found that the sensor exhibits superior selectivity towards H₂ S,and the detection limit can reach as low as 20 ppb.The sensor shows an extremely high response up to 1088% towards 10 ppm H₂ S.This value is much higher than that of other high response organic-based H₂ S sensor.3.Then we modified the surface of above-mentionedgas sensor with organic semiconductor Ph5T2,and compared the responsibility towards NO₂?NO?H₂S before and after modification.The experiment results show that the device exhibits obvious enhanced response towards oxide gas NO₂,NO,but weakened response to reducing gas H₂ Safter surface modification.And the sensor shows better selectivity towards NO₂ instead of H₂ S after surface modification.The heterojunctions between CuPc and Ph5T2 capture a lot of holes from the side of CuPc,resulting inlots of electrons accumulating at the side of CuPc near the heterojunction,and provide more adsorption sites for NO₂ and NO.So the responses are enhanced for NO₂ and NO.