Photogenerated Current Characteristics Of Two-dimensional MXenes Thin Films

Among many two-dimensional materials,MXenes,a new class of metallic carbon-nitrogen/compounds with layered structures,has attracted wide attention.Researchers have developed a photodetector based on MXenes.However,the photodetectors made with MXenes have a narrow detection band.More importantly,in the aspect of polarized light detection,only anisotropic materials are used for polarized light detection,which greatly limits the application prospect and commercial value of MXenes detector.Therefore,it is of great significance to design and prepare a large-area and wide-band self-powered polarization sensitive photodetector based on MXenes.In this paper,two MXenes detectors,Ti₃C₂T_xand Nb₂CT_z,are designed based on the photogalvanic effect(PGE).Molybdenum disulfide quantum dots were added to improve the detector performance.The main research contents are as follows:(1)Two kinds of MXenes-Ti₃C₂T_xand Nb₂CT_zwere prepared by spin coating method.The performance differences of photodetectors prepared by materials of different thickness were compared.The performance of single system Ti₃C₂T_xand Nb₂CT_zphotodetectors,including polarization extinction ratio and response time,were tested.The maximum polarization extinction ratio is 7.6 and the fastest response time is 32ms.(2)Nanodcal software is used to calculate the photocurrent generated by Ti₃C₂T_xand Nb₂CT_zmaterials with-OH and-F functional groups on the surface.According to the photogalvanic effect,it is determined that the functional groups with F and OH on the surface can better stimulate photocurrent and polarization sensitivity.(3)Photodetectors were prepared by mixing Mo S₂quantum dots into Ti₃C₂T_xand Nb₂CT_zsolutions at different ratios(1:1,1:5 and 1:10).When the ratio is 1:5,the switch ratio of the detector can be increased from 418 to 3×10⁵.The single-system MXenes photodetectors prepared by us broaden the detection band of MXenes photodetectors and all have self-powered performance.Most importantly,the detector can detect the polarization of polarized light,with a maximum polarization extinction ratio of 7.6.Finally,by combining with Mo S₂quantum dots,the dark current of the detector is further reduced and the switching ratio is improved.The results provide reference value for the preparation of large area wide band self-powered polarization sensitive MXenes photodetectors,and provide experimental guidance.