| Organic semiconductor polymers are widely used in organic electronic devices(OFET,OLED,OPV)due to their light weight,solution-processing and good plasticity properties.With the rapid development of wearables and artificial skin in the Internet of Things,the need for transparent and flexible FETs with high performance is increasing.However,to obtain the three properties of high performance,high transparency and flexibility at the same time,this kind of field effect transistor cannot be simply realized by a single organic semiconductor material,so the method of blending insulating polymer with semiconductor polymer attracted a lot of attention.The method of blending insulating polymer with semiconductor polymer can improve the mobility of the device,and obtain high transparency,flexibility and low cost organic field effect transistor devices.People tend to choose transparent insulating polymer polystyrene(PS),polydimethylsiloxane(PDMS),polymethyl methacrylate(PMMA)as insulating polymer blend with semiconductor polymer,by using the blending systems of the phase separation and microstructure to make devices high mobility,transparent and stretchable,even used as sensors used in the human body wearable device.However,the intrinsic relationships between the microstructure of semiconductor/insulating polymer blends and their charge transfer performance is still lacking.In addition,for the research of semiconductor/insulating polymer blend system,most p-type semiconductor polymers(such as P3HT and DPP2T)are selected,while the research of n-type semiconductor polymer and insulating polymer blend film is still less.In view of this,a new naphthalenedimethylimide n-type semiconductor polymer FN2200 was selected as the research object in this paper.the semiconductor polymer FN2200 was selected to study its Intrinsic charge transport characteristics,and then blended with two kinds of insulating polymers PS and PDMS to study charge transport characteristics,aggregation degree and microstructure of the two kinds of blending films,and obtain the following research results.1.Using different solvents dissolve polymer FN2200 semiconductor,by spin coating method make organic field-effect transistor devices to study the effect of different solvent conditions on the charge transport performance of FN2200.At the same time,we analyzed the state of aggregation,microstructure and morphology of FN2200 semiconductor polymers in different solvents.It is found that the FN2200 thin film grown by toluene solution has the highest electron mobility,because the molecular aggregation degree of FN2200 thin film is the strongest,and the edge-on accumulation of FN2200 is the largest component content,these structural characteristics are beneficial to the charge transfer of the field effect transistor.In addition,the effect of the device structure on the performance of the organic field effect transistor is also studied.The electron trap density at the interface between the CYTOP dielectric layer and the semiconductor layer in the top gate device is lower,so the higher mobility can be obtained.By exploring the effect of channel length on carrier mobility of OFET devices,it is found that the mobility increases significantly with the reduction of channel length of OFET devices.2.In FN2200/PS blend system,the effect of PS content on the charge transport performance of the blend film was studied.We found in the FN2200 mix with small amount(10%)of the PS,the content of edge-on structure of FN2200 molecular chains increased,which made the mobility of the blend film nearly 2 times higher than that of the pure FN2200 film.However,a large amount of PS in the blends significantly reduced the mobility of the blends.The microstructure measurement shows that this is due to the formation of phase separation structure between Fn2200 and PS in the blends,which results in the enrichment of Fn2200 components on the surface of the films.The effect of molecular weight of insulating polymer PS on the charge transport performance of the blends was studied.It was found that the performance of the blends would not be improved when the molecular weight of insulating polymer PS was reduced to 10 kDa,no matter how much the content of the PS in blend films,which might be related to the microstructure of the blends of semiconductor and insulating polymer.Finally,the effect of small molecule additive DIO on the charge transport performance of the blend film was studied,and it was found that DIO could selectively enhance the aggregation state of the semiconductor polymer,thus having a favorable effect on the charge transport performance of the blend film.3.A large amount of PDMS was mixed into the semiconductor polymer FN2200 to improve the charge transport performance and transparency and reduce the manufacturing cost.According to the UV-Vis absorption spectra test,it was found that the addition of PDMS increased the degree of aggregation state of FN2200,which had a favorable effect on charge transport.Due to the difference of surface energy,the vertical phase separation of the blend film makes PDMS suspended on the surface of the film,which plays the role of separating water and oxygen,and is conducive to improving the stability of the device.And FN2200 forms a charge transfer path at the bottom of the film,thus realizing the high performance and transparent organic field effect transistor device.In addition,the fabrication process of flexible OFET devices is also explored.By spin-coating the blend film on the PDMS wafer and transferring it to the substrate with OFET electrode,a working organic field effect transistor is realized This lays a foundation for the preparation of subsequent flexible stretchable devices.This blend system has great application potential in wearable devices and electronic skin. |
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