Research On Laser Induced Controlled Growth Of CsPbBr₃ Quantum Dots In Fluorophosphate Glass

Cesium lead halide perovskite quantum dots（CsPbX₃（X=Br,I,Cl））have the problems of poor stability and easy decomposition,which significantly restricts their application in practical device preparation.Although its chemical stability can be significantly improved by some means,the problem of poor stability under strong light irradiation is still difficult to solve.Perovskite nanocrystals embedded in glass media can effectively isolate the atmospheric environment,thus significantly improving its chemical and thermal stability,but its photostability and the mechanism of controlled crystallization still need to be further studied.In this theis,the research background of CsPbX₃ quantum dots embedded in glass is introduced in detail.Aiming at the current problem of poor light stability under strong light irradiation,pulsed laser focusing irradiation is used to study the in-situ synthesis and decomposition of CsPbX₃ quantum dots in glass matrix,so as to clarify the conditions and process of controllable growth of CsPbX₃ in glass matrix.The main research work of this paper includes:1.The use of fluorophosphate glass as the substrate to Mosaic CsPbBr₃ quantum dots can effectively reduce the hydroxyl content in the network environment of quantum dots,and ensure the stability of quantum dots to a certain extent.CsPbBr₃ quantum-dot embedded glass was prepared by melting quenching and secondary heat treatment.The glass samples were irradiated by a 355nm nanosecond pulse laser with a single pulse energy of 8m J and a repetition rate of 100 Hz to decompose CsPbBr₃ quantum-dot.The fluorescence degradation of CsPbBr₃ quantum-dot was studied under UV excitation.The glass samples treated by nanosecond pulse laser were re-heat treated to investigate the phenomenon of regeneration of CsPbBr₃ quantum dots.2.The effect of laser with different wavelength and energy on the decomposition of CsPbBr₃quantum dots was studied.A pulsed laser with a wavelength of 535nm（lower than the CsPbBr₃quantum dot optical band gap）could not decompose CsPbBr₃ quantum dots,while a pulsed laser with a wavelength of 355nm（higher than the CsPbBr₃ quantum dot optical band gap）could decompose quantum dots.The effect of 8m J pulsed laser on the decomposition of CsPbBr₃ quantum dots is greater than that of 0.8m J pulsed laser.The experimental results show that nanosecond pulsed laser irradiation can promote the optical bandgap widening of CsPbBr₃ quantum dots to a certain extent,and the larger the monopulse energy of laser,the more obvious the optical bandgap widening of CsPbBr₃ quantum dots.3.A femtosecond pulse laser of 800nm with a repetition rate of 1k Hz,pulse width of 35fs and single pulse energy of 0-250n J is used to focus the beam on the inside of the glass precursor through a high-power focusing system,and then the synthesis of CsPbBr₃ quantum dots at the fringe is induced through subsequent low-temperature heat treatment.The controllable distribution of CsPbBr₃quantum dots in glass matrix is realized.At the same time,by changing the laser energy and the subsequent heat treatment temperature,it is found that the higher the heat treatment temperature and the higher the single pulse energy of the laser,the more obvious the photoluminescence phenomenon of CsPbBr₃ quantum dots.At the same time,it is found that the fringe resolution of CsPbBr₃ quantum dots is the best when the sample is heated at 320℃for 2h and the corresponding monopulse energy is 150n J.The laser parameters are used to store 3D information in glass matrix.