Preparation And Performance Of Conformable Organic Field Effect Transistors Based On Solution-processed Method

The preparation of organic semiconductors mainly involves vapor-deposition method and solution-processed method.Compared with the vapor-deposition method,the solution-processed method shows the outstanding advantages such as low cost,low energy consumption,high yield,and large-area production.The preparation of high-performance,large-area flexible organic semiconductor devices by the solution-processed method is a shortcut to realize the low-cost preparation of flexible intelligent electronic devices.However,mostflexibleandconformabledevicesthatpreparedbythe solution-processed method use organic thin films as the active layer,the mobility of whichare generally in low level.In contrast to organic thin films,single crystals possess perfect molecular ordering and are free of grain boundaries.Experimental results have proved that high mobility and intrinsic charge-transport properties can be observed in single-crystalline transistors.And the dielectric layers extensively applied in flexible and conformable electronics are mostly soluble,which are incompatible with semiconductor solutions,resulting in failure of device fabrication.In order to solve the problems of low device performance prepared by the solution-processed method and the incompatibility between the dielectric layer and the semiconductor solution,in this paper,we have systematically studied the effects of various factors in the process of the solution-processed method on the semiconductor morphology and the field effect performance of the device.And we have improved the device performance through optimization.In addition,ananti-solventflexible dielectric layercross-linked PVA was chosen to solve the incompatibility between the dielectric layer and the semiconductor solution.The main research content is as follows:1.The small molecule semiconductor TIPS-pentacene and polymer semiconductor PCDTPT field effect transistors were prepared by the solution-processed method.We systematically studied the influence of various factors on the semiconductor morphology and device performance during the preparation process.We only obtained the single-crystal morphology of the small moleculeTIPS-pentacene.The experimental results show that the ribbon-likesingle-crystalarray with uniform large-area orientation,single width of approximately 5?m,smooth surface,and regular edge can be obtained by the inclined drop-casting method when chlorobenzene is used as the solvent and growth temperature is50°C.The maximum mobility of TIPS-pentacene field-effect transistorsbased on SiO2/Si substrate is 0.2 cm² V^-1 s^-1.2.Based on TIPS-pentacene single-crystal field effect transistors,the surface of thedielectric layerwas modified with PTS by solution-processed method and vapor-deposition method.We optimized the modification time of solution-processedmethod and the modification temperature of vapor-deposition method,respectively.The results showed thatthe maximum mobility of the device was 2.22 cm²V^-1s^-1 when the modification time of solution-processed methodis 12 h.And when the modification temperature of vapor-deposition method is 60^°C,the maximum mobility of the device is 1.41 cm²V^-1s^-1.Compared to the mobilityof the transistors based onbare SiO₂dielectric layer,the mobilityof the transistors based on PTS-modified SiO₂dielectric layerincreased by an order of magnitude.3.The high performance conformable TIPS-pentacene field effect transistor array was prepared by the solution-processed method based onanti-solvent flexible dielectric layer c-PVA.We have studiedthedevice performance and conformal capability of the array.We measured the mobility of an 8×8 device array,the maximum value is 2.22 cm²V^-1s^-1,which is the highest value of conformable TIPS-pentacene transistors that reported.After peeling off the whole device array directly from OTS modified Si substrate in all-dry process,the whole device thickness is only about 480 nm,and the device array can well conform to arbitrary objects and shows the highest mobility of 0.87 cm²V^-1s^-1 on an artificial finger nail.