Zinc Phthalocyanine Single-crystal Field-effect Transistors And Optoelectronic Properties

Organic single crystals have the perfect order of molecules and the minimized concentration of charge traps,that it is the ideal model for researching the intrinsic chargetransport properties.For the same material,the performance of the organic single-crystal field-effect transistor is better than that of the thin film device.Therefore,single crystal is one of the best choices to fabricate the high performance device.The phthalocyanine materials have been widely concerned by researchers not only because of the good chemical and thermal stability,but also the excellent electronic and optoelectronic properties.Zinc phthalocyanine(ZnPc)which has good photosensitivity is a typical p-type organic small molecule semiconductor material.ZnPc is widely used for field-effect transistors(FETs),ambipolar transistors,photovoltaic cells,etc.In this study,ZnPc single-crystal nanobelts were obtained by a physical vapor transport method.Based on ZnPc nanobelts,we fabricated the ZnPc organic field-effect transistors and researched the electronic and optoelectronic properties.Details are as follows:1.The high crystalline ZnPc single-crystal nanobelts were obtained by a physical vapor transport method for the first time.And the surface morphology of ZnPc single-crystal nanobelts was characterized in detail.The width of the nanobelts ranges from several tens of nanometers to several micrometers,and the length is from 20 to 150 ?m.2.Based on high quality ZnPc nanobelts,the field-effect transistor has been fabricated by mechanical manipulation method,and its electrical properties have been explored.In our study,we used the different dielectric to improve the performance of the OFETs.Our test results show that the field-effect mobility is as high as 0.75 cm2V-1s-1 with OTS modified SiO2 as dielectric,which is the highest value for the reported ZnPc devices until now.3.Based on the high performance ZnPc nanobelt transistors,the optoelectronic properties of ZnPc nanobelt transistors were studied.Based on the 651 nm monochromatic light as the incident light,ZnPc single crystal phototransistors show excellent photosensitive properties with the high photoswitching ratio(Ilight/Idark)of 7.34×103 and the high photoresponsivity at 1.57×104 AW-1.Our test results show that the incident light wavelength,light power density,source-drain voltage and gate voltage can all act as an independent variable to modulate the current.