The Synthesis And Properties Of Cd_1-xZn_xS?0?x?0.875? And CuInS₂/ZnS Quantum Dots

Quantum dots,being a new type of fluorescent material,has the advantages of adjustable emission wavelength,narrow half-peak width,large Stokes shift,wide color gamut and high color rendering index compared with traditional organic dye molecules and LED fluorescent materials.However,its complex synthesis method,uncontrollable synthesis process,and poor thermal stability and unclear illumination mechanism limit its further development and application.Based on this,several quantum dot luminescent materials were synthesized by simple synthesis method,and their crystal structure and luminous properties were characterized.It is hoped that quantum dot luminescent materials with excellent performance can be obtained and their potential applications can be explored.The main results are as follows:?1?Cd_1-xZn_xS?0?x?0.875?quantum dots were synthesized by solid grinding method and their properties were characterized.The obtained quantum dot material has good monodispersity,high crystallinity,and a stable crystal structure.The emission spectrum indicates that it has an orange-red emission at about 560 nm.The fluorescence lifetime of Cd_0.375Zn_0.625S quantum dots is 177.36 ns,which is much higher than the fluorescence lifetime of other common quantum dots.The thermal quenching performance of Cd_0.375Zn_0.625S quantum dots was also investigated.The results show that at 120 ^oC,the luminescence intensity still remains 46.92%of the luminescence intensity at room temperature,and only 14 nm blue shift occurs,indicating that the quantum dots have a stable crystal structure.It has broad prospects in the application of LED devices.?2?Oil-soluble CuInS₂/ZnS quantum dots with tetragonal structure were synthesized by thermal injection method,and the reaction time and coating process were monitored to explore the optimal synthesis conditions.The coating of the ZnS shell passivated the CuInS₂ quantum dots,and the quantum yield increased from 1.29%?CuInS₂ quantum dots?to 65.07%?CuInS₂/ZnS quantum dots?.In the CuInS₂ and CuInS₂/ZnS quantum dots,the main radiation transition pathway is DAP recombination,so that the half-width of the emission spectrum of the sample is wide,and the results obtained by the thermoluminescence spectra also confirm it.White light LED device was fabricated by assembling yellow light YAG:Ce phosphor,blue InGaN chip and red light emitting CuInS₂/ZnS quantum dots.When the ratio of the volume of CuInS₂/ZnS quantum dots to the mass of YAG:Ce phosphor is 0.63,the color coordinate of the white LED device is?0.3814,0.3237?and the color temperature is 3415 K,which has good practicability and applicability.?3?Water-soluble CuInS₂/ZnS quantum dots were synthesized by solution method and their synthesis conditions were investigated.Since Zn?OH?₂ is an amphoteric hydroxide,the pH of the ZnS shell solution has a significant effect on the optical properties of the water-soluble CuInS₂/ZnS quantum dots.The ZnS shell solution was prepared with Zn?oAc?₂·2H₂O at pH=10,and when the coating time was40 minutes,the obtained water-soluble CuInS₂/ZnS quantum dots had the best luminous properties.The water-soluble CuInS₂/ZnS quantum dots are co-crystallized with a saturated NaCl solution,and the obtained co-crystal salt has good thermal quenching performance.When the ambient temperature reaches 100 ^oC,the luminescence intensity of the co-crystal salt still remains 59.72%of it at room temperature,which means a significant improvement.