Performance Of Photoelectrochemical Ultraviolet Photodetector Of SnO₂ Nanosheets

Ultraviolet photodetectors can be widely used in environmental monitoring,space detection,communication and photoelectric circuits,so the demand for high-performance photodetectors is gradually increasing.Photoelectrochemical ultraviolet photodetectors with solid/liquid structures composed of semiconductors and electrolytes have attracted widespread attention due to their low production cost,good responsiveness and simple preparation process.SnO₂ is an n-type semiconductor with high electron mobility and a band gap of 3.6 e V,making it a great application prospect in ultraviolet detection.However,the poor light absorption rate of the photoanode and the interfacial charge recombination make the performance of SnO₂-based photochemical photodetectors still not meet the requirements,which limits their application.In this paper,oxygen vacancies and array structures are used to adjust the photoelectric performance of photoelectrochemical ultraviolet photodetectors based on SnO₂ nanosheets,and the specific research content is as follows:SnO₂ nanosheets were synthesized by hydrothermal method,and then the oxygen vacancies concentration of the SnO₂ nanosheets was adjusted by annealing process.Their morphology,crystal structure,element valence and oxygen vacancies concentration were characterized by scanning electron microscopy,X-ray diffraction and transmission electron microscopy.SnO₂nanosheets were assembled as photoanodes into photoelectrochemical ultraviolet photodetectors,and detection performance tests were carried out.It was found that the oxygen vacancies concentration in SnO₂ decreased significantly with increasing annealing temperature.At a bias voltage of 0.2 V,the photocurrent density of SnO₂ nanosheets-based photodetectors with different annealing temperatures first increases and then decreases,and the difference in photoresponse is due to the co-regulation of the transport of photogenerated carriers by oxygen vacancies and charge transfer at the interface.The photocurrent density was highest at 550°C,and the responsivity of the device reached 269.40 m A/W,and the specific detectivity reached2.38×10¹² Jones at 254 nm.In addition,the SnO₂-based photodetector has self-driving properties,with a responsivity of 65.08 m A/W,a specific detectivity of 2.66×10¹² Jones,and good long-term stability.To further improve the photoelectric performance of the SnO₂ nanosheets,the SnS₂nanosheets array was grown on FTO by hydrothermal method,and the density of the SnS₂nanosheets array was regulated by the reactant concentration,and SnO₂ nanosheets were further annealed.Transmission electron microscopy,Raman spectroscopy and UV-Vis absorption spectroscopy were used to test the morphology,crystal composition change and light absorption range of the SnO₂ nanosheets array.Through exploration,it was found that the concentration of precursor reactants affected the thickness and uniformity of the SnO₂ nanosheets array for the growth of FTO conductive glass.Furthermore,an ultraviolet photodetector based on the SnO₂nanosheet array prepared at the optimal concentration was constructed,which has good self-driving characteristics.The responsivity reaches 207.12 m A/W,which is approximately 5 times that of the SnO₂ nanosheets film,the response time reaches 25 ms,and it has good spectral selectivity and long-term stability.The improvement in device performance is attributed to the large specific surface area,fast carrier transport path,and strong interfacial electrochemical reaction of the three-dimensional array structure.Finally,the SnO₂ nanosheets array photoelectrochemical ultraviolet photodetector is applied to the underwater optical communication system,which can quickly identify and respond to ultraviolet light.The results of this paper prove that SnO₂ nanosheets have excellent photoelectrochemical properties and ultraviolet detection capabilities,which lays a foundation for their further application in the field of underwater ultraviolet optoelectronic devices.