Research On The Influence Of Improving The Order Of P3HT Thin Film On OFET Performance

In recent years,organic field effect transistors(OFETs)have received great attention due to their applications in fields such as flexible displays,biosensors,and portable devices.The solution method is a common experimental method for preparing OFETs.Because of its simple operation and relatively low requirements for preparation conditions and equipment,it has been favored by many researchers.Therefore,optimizing the solution method is of great significance.The organic semiconductor material used in this paper is poly-3hexylthiophene(P3HT).The performance of OFET is affected by the morphology of the active layer,the order of the polymer and the crystallinity.Therefore,studying the ordered structure of P3HT and the crystallinity after film formation are of great significance for improving the electrical characteristics of the device.First,this paper explores the effects of three solvents with different boiling points,chloroform(60℃),anisole(155℃),and o-dichlorobenzene(180℃),on the film quality and the electrical characteristics of the fabricated devices.In the experiment,spin coating was used to prepare the active layer,and the effects of different concentrations,rotation speeds and annealing temperatures on the quality of the active layer and the electrical characteristics of the device under three solvents were explored.Hexamethyldisilazane(HMDS)was used to modify the SiO2 surface.The modified surface energy decreased from the initial 44J/cm2 to 23J/cm2.The modified surface energy of the dielectric layer and the surface energy of the P3HT film Similar,the scanning image of the focused microscope showed that the number and size of the leaf-like crystals increased significantly and became larger.Then add 5%of the poor solvent cyclohexanone to the P3HT solution in o-dichlorobenzene solvent,so that the interaction force to form an orderly aggregation.Finally,a certain amount of polystyrene(PS)was added to the P3HT solution of the above experiment to prepare the OFET.The scanning image of the confocal microscope showed that when P3HT:PS=10:1,the number and size of leaf-like crystals on the film surface further increased and became larger..And the ultraviolet-visible light absorption spectrum,confocal microscope and polarized light microscope show that the order and crystallinity of the polymer molecules have been improved,and the carrier mobility of the final device is 7.06×10-2 cm2/Vs is increased to 1.05×10-1cm2/Vs,and the threshold voltage is also reduced from 16V to 5V.