Research On Encapsulation Mechanism Of CsPbBr₃ Phosphor With Porous Structure Of Aerogel And Its Application In LED

CsPbBr₃ phosphor has the advantages of narrow spectrum and high color purity,which has important application prospects in wide color gamut display and other fields.However,the low stability and packaging performance seriously restrict its practical application.The key to solve the above problems is the design and manufacture of micro-scale packaging structure matching the particle size of CsPbBr₃ crystal.Therefore,the encapsulation method for CsPbBr₃ phosphor with porous structure of aerogels is proposed.The encapsulation mechanism and optical properties of CsPbBr₃ phosphor with porous structure are studied.Finally,the fluorescent films are prepared and applied to LED devices.The main contents are as follows:（1）Encapsulation methods and properties of CsPbBr₃ phosphor based on porous structure of aerogel.The ultrasonic breaking method for CsPbBr₃ Perovskite quantum dot（PQD）solution was studied.The hole size of porous structure in aerogel matrix（Aero）was matched with particle size of PQD,so the encapsulation method of AeroPQD phosphor with porous structure was proposed and its fluorescence properties were studied.It was found that the nano porous structure and super hydrophobic rough morphology of the aerogels effectively improved the dispersibility and water stability of PQD.Therefore,the photoluminescence quantum yield（PLQY）of AeroPQD phosphor with the optimized packaging parameters was as high as75.6%,and the fluorescence intensity of AeroPQD phosphor immersed in water for 11 days had no obvious attenuation.However,AeroPQD phosphor is difficult to be directly applied to traditional solid-state LED devices due to its poor ligand stability and its toxic effect on silicone resin.（2）In-situ encapsulation mechanism of CsPbBr₃ phosphor based on porous structure of aerogel.In order to solve the problems of toxic effect on silicone resin and poor stability caused by ligands,the ligand-free CsPbBr₃ composite perovskite nanocrystal（CPNC）coated with Cs₄Pb Br₆ was prepared by ultrasonic breaking method.It was found that the PLQY of CPNC phosphor was low（up to 38%）and there was serious agglomeration phenomenon.Furthermore,the in-situ encapsulation method for AeroCPNC phosphor with porous structure was proposed,and the influence of porous structure and ultrasonic process parameters on the morphology and optical properties of AeroCPNC phosphor was revealed.It is found that the synergistic encapsulation of Cs₄Pb Br₆ and Aerois beneficial to improve the luminescent properties and uniformity of the phosphor.After optimization,the particle size distribution of AeroCPNC phosphor is mainly 1-2μm,and the fluorescence quantum yield is increased to 62%.（3）Preparation of strong scattering fluorescent film and its application in LED devices.Based on AeroCPNC phosphor,fluorescent film was prepared by solvent-free packaging process,and its dispersibility and optical properties were studied.It is found that AeroCPNC phosphor has better dispersibility in silicone resin than CPNC phosphor,particle size deviation is reduced by more than two orders of magnitude,and has better thermal stability.Due to the strong scattering characteristics caused by the size effect of AeroCPNC and its high PLQY,the green light ratio of the device is～2.7 times that of the CPNC-LED device.And the fluorescence conversion efficiency of AeroCPNC LED is still more than 30%at nearly 90%green light ratio（pure green）,which is equivalent to that of commercial phosphors.It is of great significance to promote the practical application of CsPbBr₃ phosphors.