Flexible Photodetector Based On Two-Dimensional FePs₃ Nanosheet And Its Performances

Photodetector is an optoelectronic device that can convert light signals into electrical signals.It is widely used in the fields of agricultural monitoring,imaging,optical communications,security inspection,etc.Therefore,exploring of high-performance photoelectric materials and photodetector is very important.Since graphene was successfully prepared in 2004,graphene-like two-dimensional（2D）materials have developed rapidly,which has been a fascinating field of study for researchers.High-performance electronic and optoelectronic devices based on 2D materials have been widely reported.Metal phosphorus trichalcogenides（MPT）with2D layered structure have attracted a lot of attention due to its unique physical and chemical properties.Here,we investigate the photo-response performance of 2D FePS₃nanosheets,and fabricate the flexible photoelectrochemical-type（PEC）photodetector based on 2D FePS₃.The main contents are as follows:1.The 2D FePS₃ nanosheets are successfully prepared by sonication-assisted liquid-phase exfoliation method.The 2D FePS₃nanosheets are deposited on flexible substrate as the photoelectrode to fabricate PEC photodetector device.It is found that PEC photodetector based on 2D FePS₃nanosheets has a large photocurrent density(3.2μcm^-2),a short photo-response time（256 ms of rise time and 279 ms of decay time）,and a good stability（over 1000 s）.Due to the formed electric field at the interface between FePS₃and the electrolyte,the device can work without an external power.In addition,it is interesting that that the photoelectrode can still maintain relatively stable photodetection performance after 500 cycles of bending and twisting.This work provides an effective way for the preparation of 2D FePS₃nanosheets,and gives some basis for the related application.2.In order to realize the miniaturization and practical application of the PEC photodetector,we fabricate the flexible PEC photodetector with a sandwich configuration,where solid electrolyte replaces the previous liquid electrolyte,the flexible conductive material is used as the substrate,FePS₃and FePS₃/r GO composite material are used as light-absorbing material,respectively.Furthermore,the photo-response performances of the device are investigated under different light power intensity and applied voltage.It is found that the photocurrent densities of the device are obviously dependent on the light power intensity and the applied voltage,and the photocurrent density can be improved by increasing the applied voltage.At the same time,the study also found that the device can still maintain a good photo-response performance after 1000 s.Compared to the 2D FePS₃photodetector,the FePS₃/r GO photodetector has a larger photocurrent and faster photo-response speed,which is mainly derived from the addition of r GO.The study on the performance of the device under different angles of bending indicated the photodetector has a good photo-response behavior.This work provides certain research idea and technical foundation for the expansion of PEC device application,and develops the new flexible materials and devices.