| Organic semiconductors have developed rapidly over the past few decades,shown multiple advantages in terms of molecular diversity,solution processability,lightweight,biocompatibility,and intrinsic flexibility.In this paper,organic field-effect transistors(OFET)based on poly(3hexylthiophene)(P3HT)was prepared by solution.In order to obtain the molecular packing form,arrangement order and film morphology of P3HT which are more conducive to improving the device performance,the improvement of solvent blending,annealing and spin coating technology was studied.Specific research results are as follows:1)1,2 dichlorobenzene solvent was mixed with anisole and 2-methylanisole respectively to improve the orientation of molecular chain and increase the efficiency of charge transport.When the binary solvent of 1,2 dichlorobenzene mixed with 2-methyl anisole 8:2 is used,the mobility of carrier is the highest,which increases to about 0.0372 cm2/Vs compared with 0.0059 cm2/Vs for the devices prepared with pure 1,2 dichlorobenzene solvent.The edge-on arrangement of P3HT molecules is obviously strong,and the distance between crystal faces is shortened from 1.73nm to 1.65nm.The molecular arrangement is the tightest,the exciton bandwidth is the shortest,and the conjugate length is the longest.The optimal vacuum annealing temperature at this blending ratio was explored,and the highest carrier mobility was obtained at 110℃,which was 0.0491 cm2/Vs.P3HT molecules crystallized and aggregated due to thermal motion,resulting in a complete nanowire network covering the substrate and reducing the defects between grains.2)After the optimum annealing temperature was determined,in order to prolong the film forming time and reduce the film defects,the vacuum annealing was changed to solvent vapor annealing(SVA).When the solvent vapor was adsorbed by the P3HT film,it acted as a plasticizer,and the solvent molecules diffused into the P3HT film,promoting the molecular motion of the polymer chain,thus enhancing the molecular order,and increasing the number of long nanofibers in the film.The hole transport path is improved,and the mobility reaches 0.0682 cm2/Vs.3)Based on solvent vapor annealing,Based on solvent steam annealing,the spin coating process was optimized by changing the on-center spin coating to off-center spin coating to promote the ordering of P3HT nanowires to improve the charge transfer characteristics of the films.The S2D,representing the order degree of nanowires,is increased from 0.13 to 0.51,and the device mobility finally reaches 0.0916 cm2/Vs.Compared with the original device without blending solvent,eccentric spin-coating and solvent vapor annealing,the mobility is increased by about 15 times,and the threshold voltage is reduced from 36.6V to 8.27V. |
