Fabrication Of Organic Semiconductor Micro/nanowires And Arrays By Drop-casting Method

Organic semiconductor micro/nanowires and arrrays have attracted extensive attention recently because they combine the advantages of both organic semiconductor micro/nanowires and arrays.On one hand,they have light weight,low cost,good flexibility,and electronic tunability.On the other hand,the arrays show superior advantages in the high-efficiency and large-scale micro/nanodevice fabrication.The growth of organic semiconductor micro/nanowires and arrays is desired for the further study.The representative progress is mainly performed with solution-based method,including dip coating,zone casting and drop casting.The drop-casting method is most extensively used due to its facile process and no requirement of specific equipments.In this paper,based on the traditional drop-casting method,we develop a multiple drop-casting method and a drop-casting method in the saturated solvent atomosphere.By the multiple drop-casting method,using dibenzo-tetrathiafulvalene(DB-TTF)as solute and dichloromethane as solvent,the well-aligned micro/nanowire arrays have been obtained with the success ratio as high as 94%.This method enables the arrays with a length over a few hundreds of micrometers to locate between droplets with the definite orientation.The width of the micro/nanowires is controlled via tuning the concentration of DB-TTF solution in dichloromethane.By the drop-casting method in the saturated solvent atomosphere,using tetrathiafulvalene(TTF)as solute and dichloromethane as solvent,the well-aligned single-crystal tetrathiafulvalene(TTF)microwire arrays have been obtained with success ratio as high as 86%.The key improvement over the earlier study is that the substrate is placed in an apparatus which is filled with the saturated solvent vapor at room temperature.The saturated solvent atmosphere ensures stable environment and adequate time to form the arrays with high success ratio,and to dramatically improve the crystalline quality.And individual PTCDI-C8 micro/nanowire have been achieved by this drop-casting method in the saturated solvent atmosphere.PTCDI-C8 is the typical n-type organic semiconductor,which is soluble in some common organic solvent,such as chloroform and chlorobenzene.In this work,the PTCDI-C8 micro/nanowires perform the mobility as high as 0.13 cm2/Vs in air atmosphere,which is competitive compared with the highest values have been reported.These results show the potential of the multiple drop-casting method and the drop-casting method in the saturated solvent atomosphere to form the high-quality micro/nanowires and arrays,and the assemblies of nanoscale circuits for fundamental studies and future applications.