Study On Improvement Of Luminescent Property Of Solid CdS_1-xSe_x

The ternary CdS1-xSex has a potential application in the fields of optics and luminescence due to its adjustable composition and variable emission wavelength.However,the luminescent properties of CdS1-xSex solid materials obtained by conventional methods are not ideal.Therefore,the present work is aimed to improve the property of CdS1-xSex by optimizing reaction conditions,such as selecting appropriate reaction source and reaction medium or modifying the surface of CdS1-xSex particles.The main points are as follows:1.The effects of reaction mediums on the crystallinity and luminescence of CdS1-xSex have been studied.With CdC12,thiourea,and Se powder as raw materials,CdS1-xSex has been synthesized in sodium hydroxide solution and ammonia aqueous medium respectively.It was found that the CdS1-xSex obtained in the sodium hydroxide solution medium was polycrystalline which exhibited weak luminescence and less Se content,while the CdS1-xSex synthesized in the ammonia medium was single crystal which has more Se content and strong luminescence.Moreover,the luminescence of the single crystal CdS1-xSex bulk material is better than that of the reported CdS1-xSex bulk material.2.Using CdC12,thiourea and Se powder as reaction raw materials,a series of CdS1-xSex have been synthesized in ammonia aqueous medium with different CS(NH2)2/CdCl2 molar ratio,reaction temperature,and pH of reaction system by simple hydrothermal method.The effects of different reaction conditions on the crystallinity and luminescence of the CdS1-xSex have been investigated in detail.Results reveal that the favorable molar ratio of reactant CS(NH2)2/CdCl2 is 5.0-10.0,the optimum temperature of hydrothermal reaction is 150? and the favorable pH of reaction system is about 12.0 for preparing the CdS1-xSex with high crystallinity and strong photoluminescence.3.A simple two-step method was used to enwrap the CdS1-xSex nanoparticles with CdS or ZnS shell so as to obtain CdS1-xSex/CdS or CdS1-xSex/ZnS nanocomposites in order to improve the luminescent property of CdS1-xSex.Results suggest that CdS1-xSex nanoparticles have been enwrapped with CdS or ZnS shells,the UV-vis absorption and photoluminescent spectra of the CdS1-xSex/CdS and CdS1-xSex/ZnS nanocomposites are obviously different from that of the unwrapped CdS1-xSex,and the photoluminescence of the CdS1-xSex/CdS nanocomposite is stronger than that of the unencapsulated CdS1-xSex particles.These results indicate that the luminescent properties of CdS1-xSex can be improved by surface modification.