The Research On Optoelectronic Properties Based On Bi₂O₂Se Nanosheets

Two-dimensional materials with excellent crystallinity and high surface area to volume ratio are often used to prepare photodetectors,and the prepared photodetectors have high responsivity and photoconductivity gain.Recently,a new type of two-dimensional semiconductor material Bi₂O₂Se due to its ultra-high electron mobility characteristics,suitable band gap width,good environmental stability and self-modulation doping effect,etc.,it is applied in photodetectors,field effect transistors,supercapacitors and other fields,and show excellent performance.A photodetector is an electronic device that converts optical signals into electrical signals.It has a wide range of applications in fire monitoring,industrial control,medical analysis,and optical communications.Traditional photodetectors need an external bias voltage to work continuously,which limits their application under extreme conditions and the manufacturing process is also very complicated.However,the photoelectrochemical photodetector can use the built-in electric field formed by the semiconductor and the electrolyte to work normally without external voltage.The advantages of Bi₂O₂Se and photoelectrochemical photodetectors are the starting point of this thesis.This thesis is to prepare and test the photoelectrochemical photodetectors on the basis of Bi₂O₂Se nanosheets.In the first work,we synthesized Bi₂O₂Se nanosheets with the composite molten salt method and used them as working electrodes to prepare photoelectrochemical photodetectors.Then we launched the photoelectric performance test,and the test was performed at a voltage of 0 V.So the highlight of this work is self-powered.The measured maximum responsivity and fastest response time were 20μA/W and 0.12 s,respectively.Subsequently,the time stability and cycle stability of the Bi₂O₂Se nanosheets were also tested,and the results showed that the Bi₂O₂Se nanosheets have good photoelectric properties and stability.In the second work,we synthesized Bi₂O₂Se/rGO composite materials by a mechanical composite method,and prepared a flexible photodetector based on solid-electrolyte Bi₂O₂Se/rGO.Compared with the photodetector of liquid-electrolyte,this solid-electrolyte type The photodetector has the advantages of small size,light weight and easy portability.The photoelectrochemical test results show that the Bi₂O₂Se/rGO photodetector based on solid-electrolyte has excellent photoresponse characteristics at0 V.When the optical power is 120 m W/cm²,its photocurrent density is 400 n A/cm².After different bending degrees and multiple bending times,the current value of the Bi₂O₂Se/rGO photodetector did not decrease significantly,indicating that the Bi₂O₂Se/rGO photodetector showed good flexibility.Finally,the tested Bi₂O₂Se/rGO photodetector showed good stability.Although the photocurrent decreased after 1000 s,the decreased value was within the allowable range,and the current value was 81%of the original value.The results show that the Bi₂O₂Se/rGO composite structure has great potential in the field of flexible photodetectors,and has good stability,excellent mechanical strain capacity and excellent photoelectric properties.