Synthesis,properties And Application Of All-inorganic Perovskite Quantum Dots And Hydroxyapatite Composite Luminescent Materials

All inorganic cesium lead halide perovskites(CsPbX₃,X=Cl,Br,and I)quantum dots(PQDs)with excellent optical performance and adjustable direct band gap,strong light absorption coefficient,high defect tolerance rate and a low rate of the radiative recombination characteristics in lighting and display field has great potential and prospects for development and received extensive attention of the next generation of photoelectric technology.However,despite the rapid development of PQDs,external factors such as water,light and heat are easy to promote the aggregation and degradation of PQDs,leading to fluorescence quenching,which greatly limits their practical application.Clearly,the stability and photoluminescence properties of PQDs remain key challenges for this star material.According to the above problems,this paper intends to choose hydroxyapatite as the matrix to stablize PQDs through the room temperature synthesis method,hot injection method and high temperature calcination route,and the phsae,structure,morphology,and luminescence properties of the as-obtained materials are investigated in detail.The content mainly divided into three parts:The strontium hydroxyapatite Sr₅(PO₄)₃OH(SrHAp)with mesoporous structure and defect-luminescence properties has been introduced as inorganic matrix material to modify the surface of CsPbBr₃ PQDs.A series of novel CsPbBr₃@SrHAp nanocomposites have been prepared by a simple room-temperature synthesis approach for the first time.The CsPbBr₃@SrHAp nanocomposites not only enhance the green light emission of the CsPbBr₃PQDs,but also realize the color-tunable luminescence from blue through cyan and eventually toward green emission by simply adjusting the relative composition of CsPbBr₃@SrHAp.Meanwhile,the thermal stability of CsPbBr₃ PQDs in the nanocomposites is dramatically improved by incorporating the SrHAp matrix.Furthermore,the as-obtained LED device by combining the CsPbBr₃@SrHAp nanocomposite and 365 nm ultraviolet(UV)LED chip can exhibit dazzling green light emission,which indicates potential prospects and applicability of the nanocomposites for lighting and display devices.A series of novel CsPbBr_1.5I_1.5@SrHAp nanocomposites have been fabricated by a simple one-pot hot injection method for the first time.An electrostatic interaction mechanism has been proposed to realize the in-situ growth of CsPbBr_1.5I_1.5PQDs on SrHAp nanorods with negatively charged surfaces,which have been proved by the density functional theory(DFT).The incorporation of SrHAp matrix for CsPbBr_1.5I_1.5not only greatly enhance the thermal stability but also increase the emission intensity of the CsPbBr_1.5I_1.5PQDs.More importantly,the fascinating color-tunable luminescence performance from blue through white and eventually toward yellow emission by simply changing the amounts of SrHAp matrix or excitation wavelengths.Thus,the CsPbBr_1.5I_1.5@SrHAp single matrix white light emitting phosphor can be obtained with excellent chromaticity coordinate(x,y)and CCT in the warm white region[(0.328,0.340),5698 K],which is close to the daily use of pure white light.The as-prepared LED device can exhibit dazzling white light emission by integrating CsPbBr_1.5I_1.5@SrHAp nanocomposite into a 365 nm UV LED chip,which indicates that the as-obtained CsPbBr_1.5I_1.5@SrHAp single matrix white emitting phosphor could be regarded as potential candidates for WLEDs.In order to improve the machinability of CsPbBr₃ PQDs,a green and simple calcination synthesis method at high temperature(500-800^oC)was used to in-situ encapsulate CsPbBr₃PQDs in SrHAp,taking advantage of the collapse aggregation behavior of SrHAp at high temperature.The effects of different calcination temperature and composite proportions on the phase and fluorescence properties of CsPbBr₃@SrHAp composites are investigated,and the optimal calcination temperature and composite proportions are determined.It is worth noting that the stability of CsPbBr₃PQDs maintains a fluorescence intensity of 87%after being stored in the environment for 30 days.The stable storage of CsPbBr₃PQDs at room temperature is synthesized,and finally the solid state preparation and storage of CsPbBr₃PQDs are realized.It may open up a way for the basic research of green synthesis and high storage stability of CsPbBr₃ PQDs.