Research On Growth Control And Optical Properties Of 2D Bismuthene Semiconductor Materials

Nonlinear optics is the basis of photonics,and is widely used in material analysis,optical information technology and nano-photon technology.With the deepening of the research on nonlinear optics,more and more attention from researchers have been attracted nonlinear optical materials.In this process,exploring nonlinear optical materials with high damage thresholds,large nonlinear polarizability,and appropriate response time has become a top priority in the development of nonlinear optics.Among them,some two-dimensional（2D）materials with nonlinear optical effects have also become one of the emerging research directions of nonlinear optical materials.Up to now,the nonlinear optics of 2D materials have made great progress.Bismuthene have narrow and adjustable bandgap width and high carrier mobility(5.7×10⁶cm²V^-1S^-1),which has certain potential in realizing tunable photonics research.However,the high quality and yield preparations of bismuthene have brought challenges to the above researchs.With the in-depth study of the preparation methods of bismuthene,electrochemical exfoliation method has received wide attention.Because it has the advantage of controllable preparation conditions,short time consumption,low cost,and simple operation.However,the influence of the structure and morphology of bismuthene prepared by electrochemical exfoliation on its optical properties is lack of in-depth discussion.Therefore,in this paper,we mainly carry out the research on the controllable preparation of bismuthene by electrochemical exfoliation method.On this basis,the nonlinear optical propertie of bismuthene with different morphologies are studied,and the laws between them are expounded,the main research contents are as follows:（1）The electrochemical exfoliation method can control the preparation of bismuthene.By changing the type of electrolyte washing solution（deionized water,acetonitrile solution,and 1-methyl-2-pyrrolidone solution）,bismuthene and bismuth nanoparticles with different morphologies were obtained.And it was characterized by transmission electron microscope（TEM）,atomic force microscope（AFM）,X-ray photoelectron spectroscopy（XPS）,etc.The experimental results show that when the electrolyte washing solution is deionized water,the products are monolayer bismuthene with transverse size of about 500 nm.When the electrolyte washing solution is acetonitrile solution,the products are bismuth nanoparticles with transverse size of about 20 nm and thickness of about 20 nm;Due to the small polarity of the acetonitrile solution,oxygen has an impact on it.Oxygen enters the products and form bonded oxygen,resulting in significant amorphization of the product.In contrast,the products are bismuth nanoparticles with transverse size of about 5 nm and thickness of about 20 nm when the electrolyte washing solution is1-methyl-2-pyrrolidone solution with a smaller polarity.More oxygen enter the interlayer of the products,more bonded oxygen are formed,with a deeper degree of oxidation,and almost all of the products are amorphous.（2）The influence of size on the nonlinear optical properties of bismuthene is systematically studied.A 532 nm,6 ns laser pulse open-hole Z-scan technique was used in measuring the nonlinear optical properties of bismuthene.As the intensity of incident light increases,that is,the incident energy increases,the normalized transmittance and nonlinear absorption coefficient of bismuthene gradually increase.It show excellent saturation absorption（SA）characteristics.However,under the same conditions,the reverse saturation absorption（RSA）occurs in the bismuth nanoparticles.The smaller the transverse size of bismuth particles,the greater its third-order nonlinear coefficient and the greater the transmittance.