Research On OTFT And Gas Sensitive Properties Of Polythiophene Doped With Small Squaric Acid Molecule

Organic thin film transistors（OTFTs）,as very important components in the modern electronic field,have broad application prospects in many fields such as flat panel display drivers,integrated circuits,and sensors.Because the organic semiconductor layer of the device is chemically sensitive and the device has the ability to amplify parameters in the circuit,it has attracted much attention in the field of gas sensors.Squaraine small molecule materials are considered to have broad application prospects in the field of organic solar cells because of their high absorption properties in the visible-near infrared region,strong light and thermal stability,simple synthesis method and adjustable band gap.specialty.However,there are few researches on its application in the field of organic thin film transistors.Therefore,this work will mainly study the effect of doping squaraine small molecule materials in the organic semiconductor layer of OTFT on the gas sensitivity of OTFT gas sensors,and provide a new research idea for improving the gas sensitivity of OTFT gas sensors.The researches content of this paper are:1.By doping different kinds of squaraine molecules ASQ-F,ASQ-NONE,ASQ-OME into the organic semiconductor layer,different mixed organic semiconductor layer OTFT body sensors were prepared,and different doped squaraine molecules were studied.The effects of molecules on the performance and gas sensitivity of OTFT devices were studied.Experimental results show that the doping of three squaric acid small molecule materials can significantly improve the gas sensitivity of the device.In an environment with a concentration of 30ppm NO₂,the gas sensitivity of the device doped with ASQ-F is increased to 8.56 times.The gas sensitivity of devices doped with ASQ-OME is increased to 3.39 times,while the gas sensitivity of devices doped with ASQ-NONE is only increased to 2.58 times.The analysis shows that the doping of different kinds of squaraine molecules will have a greater impact on the morphology of the organic semiconductor layer and thus affect the gas sensitivity performance.At the same time,the different functional groups contained in different materials will also affect the gas sensitivity performance of the device.2.By doping the organic semiconductor layer with different concentrations of squaraine small molecule ASQ-F,a mixed organic semiconductor layer organic thin film transistor gas sensor is prepared,which effectively improves the gas sensitivity of the device.In a 1 ppm NO₂gas atmosphere,the on-state current change rate of the device is increased to 19.77 times;in a 30 ppm NO₂ gas atmosphere,the on-state current change rate of the device is increased to 8.56 times.The analysis shows that the reason for the performance improvement is that the doping of squaraine small molecule ASQ-F in P3HT will increase the roughness of the organic semiconductor film and increase the contact area between NO₂ gas and the organic semiconductor film,which is beneficial to NO₂molecules diffuse into the organic semiconductor film,thereby improving the gas sensitivity of the device.In summary,by doping squaraine small molecules in the organic semiconductor layer of the organic thin film transistor,the gas sensitivity of the device can be effectively improved.