Study On Fabrication Process Of Organic Thin Film Transistors

Organic Thin Film Transistors(OTFTs)are made of low-cost organic semiconductors,which are the focus of researchers because of their flexibility and large-area preparation compared to inorganic materials.For example,flexible screens for mobile phones and electronic paper books,wearable sensors,memory and flexible microelectronic circuits are potential applications.However,the commercialization of OTFT devices also needs to solve practical problems such as inefficient preparation of large areas and complicated preparation processes.In this paper,a novel all-metal transfer method for preparing organic thin film transistors is proposed.By patterning the metal electrodes,the preparation of the array device is completed and its performance is tested.In the process of transferring the metal layer by PDMS template,the problem of cracking in the metal layer on the PDMS template was found.The reason why the metal crack occurred was that the thermal expansion coefficient of the PDMS template did not match the thermal expansion coefficient of the metal layer.In order to solve the problem of mismatch between thermal expansion coefficients,this paper proposes a PDMS composite template by PDMS and nanoparticle wet blending method,which reduces the thermal expansion coefficient of PDMS composite template and eliminates the PDMS composite template.Metal cracks.In addition,during the transfer process,the problem of poor quality of the metal layer transferred onto the organic semiconductor layer was also found.The adhesion work of the metal transfer process was analyzed,and the metal layer was proposed by adding the PMMA adhesion layer.Transfer quality.At the same time,the effects of temperature,pressure and thickness of the metal layer on the transfer quality of the metal layer were also discussed.Aiming at the problem of alignment error of gate electrode and source-drain electrode in array OTFT device,the cause of alignment error is analyzed,and the result is that the thermal expansion coefficient of PDMS gate electrode template does not match the thermal expansion coefficient of PMMA insulation layer.Because of the limit of the amount of nanoparticles that can be added by wet blending of PDMS and nanoparticles,the thermal expansion coefficient of PDMS gate electrode template cannot be further reduced.Based on this,we propose a microstructure based PDMS and nanoparticle dry method.The method of blending,that is,filling the nano-particles in the micro-structured silicon template,and then casting the PDMS,and after the PDMS is cured,the nanoparticles in the microstructure are coated and taken out to obtain a PDMS gate electrode template having ultra-high content of nanoparticles.The thermal expansion coefficient of the electrode template decreased by 55%.The PDMS gate electrode template prepared by the method is used to align the gate electrode with the source and drain electrodes,thereby eliminating alignment errors,and an arrayed OTFT device is prepared.In this paper,the effect of annealing temperature on the performance of Tipspentacene film is studied.It is concluded that the annealing temperature can directly affect the growth quality of the crystal of Tips-pentacene film,and thus improve the electrical properties of the device.When the annealing temperature is high,the crystal growth of the Tips-pentacene film has not been completed,the solvent has evaporated,so the crystal size is small,the performance of the device is poor;when the annealing temperature is low,the crystal growth rate of the Tips-pentacene film is relatively uniform,so the crystal size of the device is large and the performance of the device is good.Based on the above conclusions,an OTFT device with a Tips-pentacene film annealing temperature of 60 ?was prepared and its performance was tested.The threshold voltage was about-3.7V,the carrier mobility was 0.041cm2/Vs,and the on-off ratio was about 6.8×103.