Zr^(4+)掺杂CsPbI_(3)钙钛矿量子点玻璃的光学性能

Optical Properties of Zr^(4+) Doped CsPbI_(3)Perovskite Quantum Dots Glass

钙钛矿量子点具有优异的光电性能,有望应用于显示、光伏和光电探测等领域,然而,较差的稳定性限制其应用,将钙钛矿量子点嵌入到玻璃中可以有效地提升其稳定性。采用高温熔融–热处理方法制备了Zr^(4+)掺杂CsPbI_(3)量子点硼硅酸盐玻璃。结果表明:CsPbI_(3)量子点在玻璃内部析出,并且随着ZrO_(2)含量增加,由于较小直径的Zr^(4+)取代了较大直径的Pb^(2+),(200)晶面的衍射峰向大角度偏移;随着ZrO_(2)含量的增加,发光峰和吸收边均出现蓝移,荧光强度和量子效率先增大后减小,荧光寿命逐渐减小;随着ZrO_(2)含量增加,玻璃中[BO_(4)]和[SiO_(4)]四面体网络结构增加,导致玻璃三维网络结构增加,从而抑制了CsPbI_(3)量子点的析晶。本工作表明所制备的玻璃具有良好的热稳定性,能够应用于显示、照明等领域。

Introduction In recent years,all-inorganic halide perovskite(CsPbX_(3),X=Cl,Br,I)quantum dots(QDs)have attracted widespread attention due to their excellent optical and electrical properties.They exhibit high photoluminescence(PL)efficiency,narrow emission bandwidth and tunable emission energy at a wide spectral range.However,the poor stability of CsPbX_(3)QDs under ambient conditions strongly limit their applications.In this work,CsPbI_(3)QD-doped borosilicate glasses were prepared by high-temperature melting-quenching followed by heat treatment.ZrO_(2)is employed as the network modifier,which effectively modifies the local network structure of glass.By optimizing the concentration of ZrO_(2)and the heat treatment temperature or time,the PL efficiency of the glass can be effectively improved.PL intensity of the QDs glass sample demonstrates high stability,which is almost unchanged after multiple heating and cooling cycles between 293 K and 373 K.Methods The CsPbI_(3)QD-doped glasses were prepared by high-temperature melting-quenching followed by heat treatment.All raw materials with the designed ratios were accurately weighed and mixed in an agate mortar for 20 min.After the raw materials were thoroughly mixed,they were placed in a covered alumina crucible and transferred to a muffle furnace for melting at 1200℃for 20 min.Afterwards,the glass melt was quenched onto a steel plate and pressed into a glass plate.Finally,the precursor glass were heat-treated at different temperatures(520–550℃)for 4 h and at 530℃for different times(2–12 h)to precipitate the CsPbI_(3)QDs.PL spectra,PL decay curves and thermal stability of glass samples were examined with a FLS 980 fluorescence spectrometer.Optical absorption spectra were recorded by using a UV-3600UV-Vis-NIR spectrometer.X-ray diffraction patterns were recorded by using an X’Pert PRO powder diffractometer.The network structure of glass was analyzed by using a Nicolet 6700 spectrometer andan InVia Reflex Raman spectrometer.The photoluminescence quantum yield(PLQY)was measured with an absolute PLQYmeasurement system.Results and discussion From the XRD results,as the heat treatment time increases,two diffraction peaks at angles(2θ)of 28.5°and 35.5°become stronger in intensity,corresponding to the(200)and(211)planes of CsPbI_(3)QDs,respectively.With increasing theZrO_(2)concentration,the diffraction peak of(200)crystal plane shifts to a larger angle,which is attributed to the replacement of largerPb^(2+) ions by smaller Zr^(4+).Based on FTIR and Raman spectra characterizations,the network structure of glass is mainly composed of[BO_(4)],[SiO_(4)]and[BO_(3)]units.As the ZrO_(2)concentration increases,the fraction of tetrahedral network structure formed by[BO_(4)]and[SiO_(4)]units in the glass increases,leading to an increase in the fraction of the three-dimensional network structure of the glass,therefore inhibiting the crystallization of CsPbI_(3)QDs and reducing the size of QDs.This results in the blue shift of the absorptionedge and emission peak wavelength.From the emission spectra,with increasing the ZrO_(2)concentration,the PL intensity of the glasssamples first increases and then decreases.Both the absorption edge and emission peak wavelength show a clear redshift withincreasing the heat treatment temperature or time,which is mainly attributed to the increased size of QDs.According to the PL decaycurves,as the ZrO_(2)concentration increases,the PL lifetime of glass gradually decreases;as the heat treatment temperature increases,the PL lifetime of glass gradually increases.Finally,after multiple heating and cooling cycles at 293–373 K,there was no significantdecrease in the PL intensity of the glass.Conclusions The CsPbI_(3)QD-doped borosilicate glass was prepared successfully by high-temperature melting-quenching followedby heat treatment.X-ray diffraction shows that CsPbI_(3)QDs are precipitated in the glass.With increasing the ZrO_(2)concentration,thePL intensity of the glass samples first increases and then decreases,and the highest PLQY reaches 32.6%.In addition,the emissionpeak wavelength and absorption edge show a blue shift,which is attributed to the increased fraction of tetrahedral network structuresformed by[BO_(4)]and[SiO_(4)]units in the glass at higher ZrO_(2)concentrations.Consequently,the increase in the fraction of thethree-dimensional network structures of the glass impedes the movement of Cs^(+),Pb^(2+)and I^(–),inhibiting the crystallization of CsPbI_(3)QDs.After multiple heating and cooling cycles at 293–373 K,there was no significant decrease in the PL intensity of the glass,indicating that Zr^(4+) doped CsPbI_(3)perovskite QDs glass has good thermal stability,which may find applications in display,lightingand other fields.