Large-scale Fabrication Of Organic Single Crystal Field-effect Transistors And Application On Flexible Strain Sensor

Organic single crystals,compared with their thin-film counterparts,always have a highly ordered structure and less grain boundary and defects.So they have been always used to study the intrinsic charge-transport properties of semiconductor materials and fabricate high-performance optoelectronic devices.Recent years,the organic single crystals have been widely studied.However,the methods to fabricate organic single crystal field-effect transistors(OSC-FETs)can't meet the requirement of largescale and high efficiency,which limits the research about OSC-FETs.Moreover,the strain sensorsbased on flexible organic electron devices have attracted much attention.However,less works have been reported abouthow strains influencethe performance of OSC-FETs and their potential application on strain sensors.In this dissertation,CuPc and rubrene single crystals were fabricated by physical vapor transport(PVT)method.Then,the glassfiber was used as mask to fabricate large-scale devices with high efficiency.In addition,the flexible OSC-FETs were fabricated based onrubrene single crystals,and researched by applying different strains.The main results are as follows:1.CuPc and rubrene single crystals were synthesized by PVT method.Polarization microscope,XRD,and SEM were taken turns to explore the crystal structure and observe the surface appearance.A new method,named “glass fiber mask method”,was taken to fabricate large-scale OSC-FETs based on CuPc single crystals with high efficiency.The glass fibers are light-weight so that they can adhere themselves onto the surface of substrate and will be used as mask when metal deposition for electrodes fabrication.In this case,as much as 15 OSC-FETs based on CuPc single crystalswere fabricated on one substrate at the same time.The high mobility up to 0.7 cm2V-1s-1 has been realized,which is close to the reported highest value.A modified “glass fiber mask method”was taken to fabricate OSC-FETs array based on rubrene single crystals.Subsequently,the relationship between the thicknessesof rubrene single crystals and the mobility of devices was demonstrated.2.Flexible OSC-FETs based on rubrene single crystals were fabricated by a new method and measured through external circuits.All devices show high mobility,good stability and no hysteresis effects.Then,different strains were applied on the flexible devices to research the change of their electrical performance.The results of static bending test show that the mobilityincreaseswith compressive strainand decreaseswith tensile strain.Moreover,the results of dynamic bending test demonstrate that flexible OSC-FETs exhibit obvious response to different tensile strain.When the tensile strain is between-0.1% and-0.2%,the device show a high sensitivity of 123,and the response time and the recovery time are 0.9 s and 1 s,respectively.The results indicate that the flexible organic single crystal transistors can be used to detect low strain with high sensitivity and show their potential application on strain sensor.