Block Conjugated Polymer Field Effect Transistor And Its Application In Sensor

Sensors based on organic field effect transistors have high potential in civil and military applications,especially in flexible wearable devices.It is important to study high-efficiency,low-cost,high-performance sensor preparation strategies.In this dissertation,we optimized the electrical properties of the conjugated-insulating block copolymer through tailor the morphology.The self-assembly ability of the block copolymer and the insulating polymer blend system can induce block copolymer forming nanowires in PMMA matrix.The block copolymer nanowires obtained by this method achieved higher electrical properties and stability than the spin-coated block copolymer film,and the nanowire structure features a high specific surface area which can directly expose the sensing layer.Therefore,there is a strong advantage for further sensing performance testing.The main work is as follows:1)Conjugated polymers with a helical structure have been in rapid development in recent years because of their potential applications in chemical and biological sensors.We demonstrate the fabrication and characterization of helical nanofibrils of block copolymer poly?4-isocyano-benzoica cid 5-?2-dimethylamino-ethoxy?-2-nitro-benzylester?-bpoly?3-hexylthiophene??PPI?-DMAENBA?-b-P3HT?via a transfer-etching method.The density and lateral length of nanofibrils can be facilely controlled by regulating the process conditions,which,in turn,directly determine the electronic property.Organic field effect transistors based on helical nanofibrils were successfully fabricated with the highest mobility of9.1×10^-3 cm²V^-1s^-1,an on/off ratio of 3.4×10⁵,and high bias stability.The helical nanofibrils were proved to be beneficial for obtaining a highly sensitive and selective chemical sensor.And,the transistor based on helical nanofibrils exhibits a relative response of 28.6%to 100 ppb ammonia,which is even much higher than the responses to 1 ppm ammonia for homo poly?3-hexylthiophene?nanofibrils?7%?and block copolymer nanofibrils without helical structure?0.9%?.The combination of helical structure with nanofibrils may provide a new strategy to fabricate high-performance chemical sensors suitable for use in environmental monitoring,industrial and agricultural production,health care,and food safety.2)Solar-blind deep ultraviolet photodetectors?DUVPDs?have recently attracted huge research interest due to their promising applications in various fields.However,the fabrication of DUVPDs are dominated by ultrawide band semiconductor materials such as Ga₂O₃,Zn_xMg_1-x-x O,diamond and Al_xGa_1-xN,which usually entails the usage of complicated instruments.In this study,we report on the development of a sensitive solar-blind DUVPD and flexible image sensor by using solution-processed P3HT-b-PHA nanofibrils as building blocks.The P3HT-b-PHA nanofibrils fabricated by a transfer-etching method has a diameter of 14-18 nm and a hole mobility 0.04cm²V^-1s^-1.Device performance analysis reveals that the P3HT-b-PHA nanofibrils based PD was highly sensitive to DUV irradiation with wavelength of 254 nm,but is virtually blind to both 365 nm and other visible light illumination.The observed solar-blind photoresponse is due to the unique optical property of the ultrathin nanofibrils.The responsivity is 120 A/W,with external quantum efficiency up to 50000%.Moreover,a flexible image senor on plastic substrate with 10×10 pixels was successfully fabricated which can record an“UV”image with and without bending.These results show that the present P3HT-b-PHA nanofibrils are ideal building blocks for assembly of high-performance DUVPDs.