Investigation Of Crystallization And Reversible Luminescence Properties Of Perovskite Quantum Dot-doped Glass Manipulated By Optical And Thermal Field

Metal halide perovskites(MHPs)possess excellent optoelectrical properties such as strong light absorption coefficient,high photoluminescence(PL)quantum efficiency,tunable band gap,and long carrier diffusion length.In the past 10 years,MHPs have achieved a great breakthrough in optical and optoelectrical devices such as solar cells,displays,photodetectors,and laser.Owing to the quantum confinement effect and the unique exciton fine structure,perovskite quantum dots(QDs)exhibit better optical properties compared to their bulk counterparts.However,perovskite QDs with large surface-to-volume ratio are more vulnerable to high temperature,strong light irradiation,humidity,oxygen,and other external environmental stress,leading to damage of crystal structure and decrease of their optical performance.The instability of MHPs is blamed for their intrinsic ionic crystal structure.The formation energy of perovskite QDs is low,thus,their stability is poor,but at the same time,perovskite QDs have self-healing ability.There are two strategies to improve the lifetime of perovskite QDs and their devices:1.Improve the stability of perovskite QDs,thus slowing down the decline rate of their performance;2.Restore the performance of perovskite QDs after degradation to extend their lifetime.Coating perovskite QDs with a dense inorganic glass network can isolate QDs from the external harmful environment,and avoid the aggregation and the secondary growth of the QDs,which is one of the effective methods to improve the stability of the perovskite QDs.Therefore,this paper mainly focuses on the fabrication and optical properties of perovskite QD-doped glass.For the first time,we use the optical and thermal field to manipulate the crystallization behaviors and reversible optical performance of perovskite QDs inside the glass.Moreover,the interaction between light and perovskite QDs is further explored.This strategy is promising to expand the applications of perovskite QDs in reversible X-ray imaging,three-dimensional(3D)display,3D optical information storage,optical anti-counterfeiting,and information encryption.Our detailed research includes the following four parts:(1)The perovskite QD-doped glass was prepared by melt-quenching method and post thermal treatment,achieving tunable narrow-band PL covering the whole visible region and the improvement of chemical and thermal stability.Through the selection and design of glass compositions and the regulation of halogen ratio,tunable narrow-band PL can be achieved,which can cover the whole visible region(400-750 nm),and the highest PL quantum efficiency can reach 50%.(2)Perovskite QD-doped glass showed tunable scintillating luminescence covering the whole visible region and comparable scintillation properties to commercial Bi₄Ge₃O₁₂(BGO)crystals.In addition,the reversible luminescence of the perovskite QD-doped glass can be manipulated by X-ray irradiation and low-temperature heat treatment.Based on the unique exciton fine structure and quantum confinement effect,the perovskite QD-doped glass can achieve scintillating luminescence intensity comparable to the commercial BGO crystals with linear X-ray response with a slope of 3.78,and the X-ray detection limit of 2.34?Gy s^-1.Besides,due to the low formation energy of perovskite,the PL intensity of perovskite QD-doped glass will gradually decline under continuous X-ray irradiation.Nevertheless,the PL intensity of perovskite QD-doped glass can be restored by low-temperature heat treatment.By using this feature,we proved that reversible X-ray imaging can be achieved on the surface of perovskite QD-doped glass through X-ray irradiation and thermal treatment,which expands the application of perovskite QD-doped glass in the field of high-energy ray detection and imaging.(3)Formation and reversible PL of perovskite QDs in glass can be manipulated by femtosecond laser irradiation and low-temperature thermal treatment.Femtosecond laser with extremely high peak power can interact with glass matrix through a nonlinear multi-photon absorption process.Femtosecond laser irradiation was used to destroy the structure of the glass network,promoting atomic migration and rearrangement to form crystal nuclei.And then the crystal nuclei grew into perovskite QDs under low-temperature thermal treatment.Therefore,PL can be obtained from the femtosecond laser-irradiated regions,realizing the space-selective formation of perovskite QDs in the glass.Due to the ionic crystal structure and low formation energy of perovskite QDs,high-energy femtosecond laser irradiation will quench the PL of perovskite QDs.And low-temperature thermal treatment can drive the constituent elements in the glass to heal the structure and defects of the perovskite QDs,to recover the PL of the perovskite QDs.Femtosecond laser processing has the advantages of high precision,high efficiency and high spatial resolution.Therefore,two-dimensional(2D)and 3D emission patterns containing perovskite QDs can be realized in transparent glass by combining femtosecond laser irradiation with an electrical-driven 3D translation platform.Based on reversible PL manipulated by laser irradiation and thermal field,perovskite QD-doped glass can realize 3D display,3D rewritable optical information storage,and optical anti-counterfeiting.(4)By using femtosecond laser irradiation,perovskite QDs can be directly crystallized on the glass surface.And the reversible spectral changes of the perovskite QDs can be manipulated by ultraviolet(UV)light.Since the surface energy of the glass is high,the formation of perovskite QDs was induced directly on the surface of glass by femtosecond laser irradiation without post Thermal treatment.The glass network structure of the glass surface was destroyed by femtosecond laser irradiation leading to the reduction of the crystallization barrier on the glass surface.Moreover,continuous high-power UV light irradiation can induce the formation of perovskite QDs in the femtosecond laser-irradiated region.For Cs Pb Br₃ QD-doped glass,UV light irradiation can enhance its PL intensity.But for Cs Pb(Cl/Br)₃ QD-doped glass,the high-power UV light irradiation can induce the formation of Cs Pb Br₃ QDs to slowly change the luminescence of the glass sample from blue light to green light.There is a competition to obtain Br element between the Cs Pb Br₃ QDs and Cs Pb(Cl/Br)₃ QDs,which led to the PL reduction of Cs Pb(Cl/Br)₃ QDs and the PL enhancement of Cs Pb Br₃ QDs under UV light irradiation.However,in the darkness,Cs Pb Br₃ QDs induced by UV light irradiation will undergo rapid ion exchange reaction with Cl elements to form Cs Pb(Cl/Br)₃ QDs,leading to the recovery of the luminescent color.The reversible luminescent color of Cs Pb(Cl/Br)₃ QD-doped glass surface-crystallized by femtosecond laser irradiation can be manipulated by UV light irradiation,providing important insights into the formation of light-induced perovskite QDs and the mechanism of the interaction between light and perovskite QDs,and meanwhile,endowing perovskite QDs-doped glass better optical anti-counterfeiting performance.