Preparation And Photoelectric Properties Of Copper-based Ternary Chalcogenide Nanomaterial

In recent years,copper-based ternary chalcogenide nanomaterials have been widely used in solar cells,photodetectors,photocatalytic hydrogen production,thermoelectric materials and tumor therapy due to their advantages of comparatively abundant elements,high optical absorption coefficient,low toxicity and adjustable bandgap energy.It is well known that the performance of materials is influenced by their composition,structure,morphology and size.Therefore,it is of great significance to design a simple,easy-to-manipulate and low-cost synthesis method to realize the effective regulation of the phase structure,composition and morphology of the new copper-based ternary chalcogenide nanomaterials,which is of great significance for understanding the growth mechanism of nanocrystals and improving the application performance of materials.This thesis aims to explore the development of solution-phase synthesis methods to control the preparation of novel multifunctional copper-based ternary chalcogenide nanomaterials.In the experimental process,based on the principle that thermodynamic and kinetic factors affect the solution-phase synthesis of crystals,we have creatively explored the experimental conditions to control the synthesis of functional inorganic nanomaterials with novel structures.In this paper,several typical copper-based ternary chalcogenides were selected as the research objects.The controllable synthesis of CuGaSe₂,Cu₂GeTe₃ and Cu₃NbSe₄ nanocrystals was realized by a hot-solution injection method and the growth mechanism was discussed.Based on the crystal structure,surface structure and band structure of nanomaterials,their photoelectric properties were preliminarily studied.The main research results are as follows:1.The controllable synthesis of non-layered two-dimensional（2D）CuGaSe₂nanosheets was realized by solution-phase synthesis method.In the experiment,we chose anhydrous cuprous chloride,gallium acetylacetonate and diphenyl diselenide as precursors,1-octadecene,oleic acid and oleylamine as reaction media,two-dimensional CuGaSe₂ nanosheets with tetragonal phase,uniform size and morphology were prepared by a hot-solution injection method and organic ligand assisted growth method.Meanwhile,the growth mechanism of plate-like CuGaSe₂was proposed.The optical and photoelectric performance tests based on CuGaSe₂nanosheets show that the plate-like CuGaSe₂ nanocrystals synthesized in this work have high light absorption capacity and excellent photoelectric properties,revealing that CuGaSe₂ nanosheets have potential application prospects in photoelectric conversion.2.A“bottom-up”method was developed to synthesize ternary Cu₂GeTe₃nanocrystals.High-quality Cu₂GeTe₃ nanocrystals with uniform shape and monodisperse were synthesized by solution-phase synthesis method.XRD,TEM,XPS and EDX measurements show that the obtained nanocrystals are pure cubic Cu₂GeTe₃.Optical characterization demonstrates that Cu₂GeTe₃ nanocrystals have a broad absorption in the visible to near-infrared region.Furthermore,an optoelectronic device based on Cu₂GeTe₃ nanocrystals exhibits excellent stability,reproducibility and responsivity.The novel synthetic route presented here not only can open a new avenue for fabricating Cu₂GeTe₃ nanocrystals,especially at the nanoscale,but also may further expand their applications.3.Monodisperse Cu₃NbSe₄ nanocrystals with uniform size and morphology were successfully synthesized by a hot-solution injection method using anhydrous cuprous chloride,niobium（V）chloride and diphenyl diselenide as precursors,oleylamine as solvent and surfactant.Studies of the formation process disclose that the reaction temperature,time and surface ligand play significant roles in determining the crystalline phase,size and morphology evolution of the Cu₃NbSe₄ nanocrystals.Photoelectric performance tests show that a Cu₃NbSe₄-based photodetector exhibits a high I_light/I_dark ratio of 35,fast response speeds of 0.3/0.1 s for rise/fall times and excellent stability,indicating its robust potential for application in electronics and optoelectronics.