Research On Preparation And Properties Of Perovskite Quantum Dots Glass

In recent years,all-inorganic lead cesium halide perovskite quantum dots(QDs)materials have received extensive attention due to their extraordinary optoelectronic properties.The instability of all-inorganic perovskites and poor understanding of the photoluminescence(PL)mechanisms have hindered their practical applications.Therefore,it is crucial to explore new methods for preparing perovskite materials with excellent stability.In this dissertation,through the control of melt-quenching method and heat treatment temperature,the lead halide cesium perovskite QDs are precipitated in a stable inorganic glass matrix.Compared with other perovskite materials,lead halide cesium perovskite QDs glass has excellent stability and environmental protection performance under the protection of dense glass structure.At the same time,such materials have high transmittance and high photoluminescence quantum yield(PLQY).By further optimizing the Cs₂CO₃ proportion,the change of Br introduction source(NaBr/KBr)and the doping of rare earth Tb³⁺ions in the matrix glass,a variety of perovskite QDs with different phases were prepared for the first time.The structure,phase,morphology and photoluminescence mechanism of perovskite QDs glass with different phases have been deeply studied.The results show that the crystal phase,morphology,and PL properties of the Cs₄PbBr₆ QDs glass,which were different from those of the CsPbBr₃QDs glass,provided distinct insights into the controversial origin of the optical properties of Cs₄PbBr₆,excluding the influence of the coexisting CsPbBr₃ and Cs₄PbBr₆.The application of the above-mentioned materials in white light emitting diode(WLED)devices,up-conversion luminescence(UCL)and X-ray photoluminescence has been further studied.This work provides the possibility for the design and practical application of perovskite nanocrystals in optoelectronic devices.The specific work includes the following points:(1)A series of 3-D CsPbBr₃ QDs and 0-D Cs₄PbBr₆ QDs multi-component glass with different phases were successfully prepared through melt-quenching method and the control of Cs₂CO₃ concentration.These results could be attributed to the different Cs:Pb stoichiometric ratio,the establishment of a Cs-rich environment,and the rhombohedral Cs₄PbBr₆ QDs self-crystallization in glass.Cs₄PbBr₆ displayed unique luminescent properties in correlation with the intrinsic defect states in the mid-band gap.(2)3-D CsPbBr₃ QDs multi-component glass has the minimum QDs grain size(about1.96 nm)and a higher exciton binding energy(?362±18 me V).Such material exhibits good PL properties and excellent stability to air,light and water.For the water resistance evaluation,the 3-D CsPbBr₃ QDs multi-component glass has a very low migration amount of lead,indicating that the such material with excellent environmental performance was much greater than that of any previously reported perovskite glass materials.The temperature-dependent reversible PL linear response and heat cycling experiments of 3-D CsPbBr₃ QDs multi-component glass indicating that they could be potential candidates for temperature sensors.At the same time,UCL was realizes in 3-D CsPbBr₃ QDs multicomponent glass(excited by980 nm)for the first time.(3)0-D Cs₄PbBr₆ QDs glass prepared at the optimal heat treatment temperature has a more stable structure,a high transmittance(?90%),a narrow full width at half maximum(FWHM,?20 nm),a high PLQY(?22%)and a superior stability which is a novel addition to the literatures.The reversible,linear,fluorescence response of Cs₄PbBr₆ QDs glass to temperature made it a potential candidate for use in low-cost thermometers.Furthermore,a high performance WLED device was fabricated.Concurrently,Cs₄PbBr₆ QDs glass as an optical gain medium to realize up-conversion luminescence under 980 nm excitation for the first time.(4)The Br constituting the perovskite QDs component is provided by KBr,such type of perovskite quantum with low ions mobility,and the perovskite QDs difficult to obtain pure phase,and then obtained a series of CsPbBr₃/Cs₄PbBr₆ and Cs₄PbBr₆/CsPbBr₃ QDs multi-component glass.Due to the protective effect of the denser glass matrix and the passivation effect of K⁺on the QDs defects in the glass,the two kinds of composite component glasses have higher PLQY(?28%;?26%).Without lead migration was detected in the water resistance test,indicating that the two types of perovskite QDs glass have the best environmental performance reported in the literature.At the same time,two kinds of composite perovskite QDs multi-component glass realized 980 nm excited UCL and X-ray excited luminescence.(5)Rare earth Tb³⁺ions with a rich 4f-4f and 4f-5d transition energy level structure,a long fluorescence lifetime,and a wide emission wavelength range.By adjusting the Tb³⁺doping concentration,a series of Tb³⁺doped 0-D Cs₄PbBr₆ quantum multi-component glass were successfully prepared.The PLQY(?31%)of Tb³⁺doped 0-D Cs₄PbBr₆ QDs multi-component glass is greatly improved through the energy transfer between Tb³⁺ion and perovskite band gap.