Preparation And Luminescence Properties Of InP/ZnS Quantum Dots

With the development of display technology,Micro-LED display technology is considered to be the next generation of display technology because of its advantages such as higher brightness,color reproduction,and response speed.Colloidal InP quantum dots are essentially non-toxic,and have the advantages of an emission range covering the entire visible light region,from blue light 480 nm to red light 640 nm,good stability,good monochromaticity,etc.Because of its excellent light-emitting performance and low toxicity,it can meet the needs of the size,optical performance and commercialization of Micro-LED luminescent materials,and is considered to be the most potential material for Micro-LED.However,the difficulty of controlling the size of InP quantum dots and the complex synthesis process hinder their development and application.Based on these problems,this paper combined with the traditional method of adjusting the size of quantum dots,proposed a novel method to adjust the size of InP/ZnS quantum dots,obtained a series of light-emitting quantum dots and studied its crystal structure and light-emitting properties.It mainly includes two parts of work:(1)InP/ZnS quantum dots were prepared by hot injection method.X-ray diffraction patterns and TEM images showed that the obtained quantum dots had a zinc blende structure,with good crystallinity and no agglomeration.The effects of the types of indium precursors,the proportion of reactive elements,the types of shell materials and the thickness on the luminescence performance of quantum dots were studied.Because the reactant phosphine can suppress the quantum dot size dispersion and the reactant zinc can pass the quantum dot luminous efficiency,under the conditions of P: In=3.6: 1 and Zn: In=5: 1,InP/ZnS quantum dots with good light-emitting performance is obtained.The coating of the ZnS shell successfully passivated the defects on the InP surface,and the fluorescence quantum efficiency was increased from less than 1% to 50%.The reasons for the blue shift of the emission wavelength and the broadening of the emission peak along with the shortening of the nucleation time are studied.It is believed that there was not enough time to focus the size of the quantum dots during the diffusion-controlled growth stage,which caused the broadening of the emission peak.(2)The surface of In-Y zeolite with a three-dimensional regular pore structure is used as the nucleation site of quantum dots to control the nucleation process of quantum dots and suppress the size dispersion of quantum dots.The principle of zeolite as a quantum dot nucleation template to control the size and distribution of quantum dots was studied.By changing the amount of zeolite to control the number of nucleation sites and control the size of InP/ZnS quantum dots,at the same time,it is no longer necessary to shorten the nucleation time to obtain short-wavelength quantum dots.The growth time of quantum dots in the diffusion-controlled growth stage increases,and the self-focusing of the particle size reduces the half-width of the quantum dots.The emission range of the obtained InP/ZnS quantum dots is 589nm-518 nm.The effect of two stages of quantum dot nucleation on the size distribution of quantum dots was studied.In the diffusion-controlled growth stage,the quantum dot size became uniform over time,and during the Oswald ripening stage,the quantum dot size become scattered over time.By changing the nucleation time,the optimal nucleation time for quantum dot synthesis was obtained,the monochromaticity of the product quantum dots was significantly improved,the minimum half-peak width of the obtained InP/ZnS quantum dots was 48 nm,and the quantum yield was close to 50%.Finally,a blue chip was used to excite commercial YAG yellow powder and red emitting InP/ZnS quantum dots to prepare a warm white LED,the color temperature of the LED is 3240 K,and the color rendering index is 86.3.