Research On Flexible Broadband Photodetector Based On Tungsten Disulfide Two-dimensional Material

As an important part of optoelectronic devices,photodetectors,especially flexible photodetectors,have a wide range of applications in national production,life and defense military fields.In recent years,two-dimensional material photodetectors have attracted more and more attention and have been extensively studied.Due to the quantum confinement effect,two-dimensional materials exhibit fascinating properties in the fields of optics and optoelectronics.In addition,due to the thickness of the atomic layer,the two-dimensional material also shows good flexibility and transparency,which has great application prospects in the emerging fields of optoelectronic device integration and wearable electronic equipment.This paper mainly starts from the two-dimensional material of tungsten disulfide and focuses on the performance of the prepared tungsten disulfide photodetector.The main contents are as follows:First,tungsten disulfide nanosheets were successfully prepared by hydrothermal intercalation exfoliation with lithium ion,and characterized by scanning electron microscope,atomic force microscope,Raman and XRD.The results show that we have prepared tungsten disulfide nanosheets with different layer structures from a few nanometers to 100 nm in thickness.This change in thickness will cause a change in the bandgap of tungsten disulfide,which is helpful for the development of broadband photodetectors.Second,through processes such as vacuum suction filtration and thermal evaporation deposition,we have developed a flexible broadband photodetector based on tungsten disulfide nanosheets films on the filter paper substrate.The device exhibits a broadband response from visible light(532 nm)to near infrared light(1064 nm).Under 532 nm light with an intensity of 59.09 m W/cm~2,the photodetector's responsivity and specific detectivity reach 4.04 m A/W and 2.55×10~9 Jones,respectively.In addition,the device still exhibits a stable and repeatable light response under the bending conditions of 0.75 cm and 1.5 cm radius of curvature.After 200 bending cycles,although the photocurrent of the device shows a downward trend,it still remains at 80%of the initial value.Third,using the electrospinning process,we successfully prepared a carbon fiber substrate with better flexibility and heat resistance,and characterized it by scanning electron microscope.As a result,it is found that the interwoven carbon fibers with different directions and a large aspect ratio make the carbon fiber substrate very flexible.Subsequently,a heat-resistant flexible broadband photodetector based on tungsten disulfide nanosheets is prepared on the carbon fiber substrate by the method of drip coating,and systematic photoelectricity test is performed under visible light at 660 nm and near infrared light at 808 nm.It is worth noting that after as many as 500 bending cycles,the photocurrent hardly drops.Compared with the previous work,the flexibility of the device is improved.In addition,after annealing at 50?to 250?,the device itself is not damaged,and its photocurrent remains stable.