The UV-NIR Dual-band Photodetecting Performances Of ZnO-graphene Composite Nanomaterials

Photodetector is a device that uses photoelectric effect to convert optical radiation into electrical signals,which is an indispensable and important part of modern opticelectronic systems.According to the response range of wavelength,photodetectors can be subdivided into ultraviolet detectors,visible light detectors,near-infrared detectors and infrared detectors,which plays an important role in applications of image sensing,communications,and environmental monitoring.Using composite detectors with different waveband responses to obtain different target information is one of the important ways to improve the accuracy of photoelectric detection and reduce the false alarm rate of the detection system.The detection bands of currently widely studied multi-band detectors are mainly focus on the visible-infrared and medium wave-long wave infrared wave bands.To achieve monolithically integrated UV-NIR dual band photodetectors at room temperature,we designed a graphene-ZnO composite nanomaterial photodetector based on inkjet printing technology and investigated the UV-near infrared photodetection performance of the composite structure of ZnO nanorods and graphene.This paper mainly studied the following aspects:1.Graphene,as a two dimensional monolayer building block of a carbon allotrope,demonstrate the high electron mobility,high transmittance,high thermal conductivity and adjustable Fermi energy features.Furthermore,it has many potential applications for electronic and optoelectronic devices,energy storage and sensor.In this paper,graphene is prepared by redox method.Compared with micromechanical separation and chemical vapor deposition(CVD),it has many advantages such as high yield,simple process and easy surface modification.It is the main method for realizing graphene-based composite functional materials.In our work,we have configured GO aqueous solution of suitable viscosity through regulating the ratio of GO and propylene glycol.By this way,graphically translucent and flexible graphene films were prepared on PET substrate by inkjet printing method and reduced by heat treatment and chemical method.2.The third generation semiconductor ZnO is a direct bandgap semiconductor with a bandgap width of 3.37 eV,and its exciton binding energy is as high as 60 meV.It is also widely exist on the earth and has little pollution to the environment.Therefore,it is expected to become a hot spot of wide band gap semiconductor devices.In this paper,Zinc oxide nanorods were grown on graphene films covered with seed layer by solution method in this paper.A photodetector based on zinc oxide-graphene composite nanomaterials was constructed and a series of photoelectric performance tests were completed.After studying the device response to ultraviolet-visible-near infrared current response curve,a noticeable response to light wavelengths at 365 nm and 980 nm was observed,responsivity reached 73.5 mA/W and 30.8 ?A/W respectively,while the response to visible light was almost none.Then,the data was fitted to the response time curve,and the device's photoelectric performance under the flexible condition was tested.It was found that the response was slightly attenuated as the bending degree increased.