The Research Of High Mobility Conjugated Polymer Field-effect Transistor Devices

Over the past few decades,solution-processible organic thin-film devices have reached stage from basic research to industrialization.Compared with inorganic electronic products,application value of organic thin-film device lies in light,preparation simple,low cost,and flexible,etc.Field-effect transistor?OFET?as the basic unit of the thin-film device,carrier mobility is one of the important parameters,which have reached a high level.The carrier mobility of p-type orderly fiber membrane devices has more than 40 cm²V-1s^-1.Relative to p-type material,n-type polymer device also was necessary part of low-power logic circuit and organic optoelectronic devices,but high performance n-type of material were very few,with bad filming and stability,corresponding OFETs device stability were also poorer.So far few n-type polymer devices with excellent performance have report,and the mobility greater than2 cm²V-1s^-1was very little.Therefore,the stable n-type polymer devices are a major challenge in the development of organic electronics.At the same time,the development of basic theory was relatively backward relative to the performance of polymer field-effect transistor.To solve above problems,this paper choose the reasonable device structure enhance the stability of materials,optimize the device structure to improve device performance,modified semiconductor/dielectric interface layer to improve forming and control the distance of ?-?accumulation,orderly film preparation to study the relationship for the molecular structure,condensed matter assembly and device performance.The main research content is as follows:1.Comprehensive excellent n-type organic semiconductor materials to design synthesis polymer PNBO,which has conjugated polymers skeleton of alternating A1-D-A2-D.Electron acceptor 1 is the strongly electronwithdrawing benzo[c][1,2,5]oxadiazole?BOZ?unit,electron acceptor 2 is naphthyl imide derivatives.Oxygen atoms of BOZ have strong electronwithdrawing ability,reducing the HOMO/LUMO energy levels of PNBO,which enhances the electronic injection and prevented hole injection from Au electrode.Heat treatment and fine modified interface layer can improve condensed matter structure and control the distance of ?-? accumulation distance.Optimization the top gate bottom contact device structure by reduce the substrate size and thickening insulating layer to improve the mobility of field-effect transistors,and the encapsulation effect of dielectric layer and gate electrode greatly enhances the stability of the device which the maximum electron mobility was 2.43 cm²V-1s^-1.The results provide certain guiding significance for n-type polymer devices and design synthesis of n-type polymer materials.2.Design synthesis high performance ambipolar organic semiconductor materials.Introduced acceptor 1 is the weak electronwithdrawing benzothiadiazole?BTZ?unit to regulate filming of polymer and energy level structure,electron acceptor 2 is naphthyl imide derivatives.Introduced selenophene to improve assemlbe between molecular chains,reduced the energy level of LUMO,and improve the mobility.At the same time,introducing electronwithdrawing group would reduce the solubility and film form property will be bad.Molecular weight distribution was confirmed to adjust the solubility,grain size,crystalline,and then more conducive to carrier transmission.Heat treatment and fine modified semiconductor/dielectric interface layer improve condensed matter structure and control the distance of ?-? accumulation distance.Decrease the work function by modified source-drain electrode to reduce energy level difference between electrode and semiconductor and reduce the injection barrier.Optimization device structure of the top gate bottom contact improve the performance of field-effect transistor,the encapsulation effect of dielectric layer and gate electrode greatly enhances the stability of the device which the maxmuim electron and hole mobility were 8.7 and 1.9 cm²V-1s^-1,respectively,and the electron mobility was the highest performance in conjugated polymers devices.The results provide certain guiding significance for ambipolar polymer devices and design synthesis of ambipolar polymer materials.3.Preparation highly crystalline polymer condensed matter thin-film to study the relationship for molecular structure,condensed matter assembly,and the carrier mobility of OFETs,then analyze carrier transmission theory.Prepared orderly fiber membrane device based on PDDPTz BT by the method of solution-shearing,mading devices in the different direction and the maxium mobility reached up to 10 cm²V-1s^-1,which was three times than prepared by the method of spincoating.Study the relation between the performance and condensed matter by doping insulation material,which proved the charge transport anisotropy in the orderly fiber film and mainly along the main chain direction.Unlike the film prepared by spincoating,edge-on accumulation pattern was given priority to molecular arrangement in highly ordered of polymer film,the good accumulation model was one of the reasons for excellent electricity performance.Test PDDPTzBT device electrical performance in vacuum,the mobility rised as the temperature showed that the carrier transport was hopping mode.The results provide certain guiding significance for polymer field-effect transistor theory development and the preparation of high-performance field effect transistor.