【摘要】 采用热注入法合成了具有不同Al³⁺离子掺杂浓度的铯铅溴（Cs Pb Br₃）量子点，并系统地研究了它们的光学特性和材料特性。研究结果表明，Al³⁺离子掺杂不仅能够有效调控Cs Pb Br₃量子点的发光强度与发光波长，还增强了Cs Pb Br₃量子点中的Pb—Br键的相互作用，从而显著提高了量子点的环境稳定性。此外，Al³⁺离子的半径远小于Pb²⁺离子，导致Al³⁺离子掺杂能够有效引起Cs Pb Br₃量子点晶格收缩，进而减小了量子点的尺寸并提高了尺寸均一性。Cs Pb Br₃量子点尺寸的减小增强了其量子限域效应，使得量子点的单光子发射性能得到了显著提高。本研究为优化钙钛矿量子点单光子源性能提供了新思路，也促进了新兴钙钛矿单光子源领域的发展。更多还原

【Abstract】 Objective In quantum communication,achieving efficient transmission and long-distance communication relies on an ideal single-photon source.Cs Pb Br₃ quantum dots hold significant promise as single-photon sources due to their high probability of single-photon emission.Among the methods to enhance Cs Pb Br₃ quantum dots’single-photon performance,size reduction is crucial.In this study,we synthesize Cs Pb Br₃ quantum dots doped with varying concentrations of Al³⁺ions using a thermal injection method and systematically investigate their optical and material properties.The results demonstrate that Al³⁺ion doping effectively modulates the emission intensity and wavelength of Cs Pb Br₃ quantum dots while enhancing the interaction of Pb—Br bonds,thus significantly improving their environmental stability.Moreover,by leveraging the smaller ionic radius of Al³⁺ions compared to Pb²⁺ions,Al³⁺ion doping effectively induces lattice contraction in Cs Pb Br₃ quantum dots,leading to reduced size and enhanced size uniformity.Consequently,the reduced size enhances the quantum confinement effect,significantly improving single-photon emission performance.This study presents new strategies for optimizing perovskite quantum dot single-photon sources,advancing the development of perovskite single-photon sources.Methods We utilize a hot injection method to synthesize Cs Pb Br₃ quantum dots and Al³⁺-doped Cs Pb Br₃ quantum dots,ensuring high crystallinity and superior size uniformity.The method involves two steps.First,a mixture of cesium carbonate,oleic acid,and octadecene is heated for 2 h in an inert environment.To enhance the synthesis quality of quantum dots,an excess of oleic acid is added,resulting in a cesium oleate precursor that is soluble at room temperature.Second,a mixture of lead bromide,aluminum bromide,oleic acid,oleylamine,and octadecene is heated for 2 h in an inert environment.This is followed by the rapid injection of 0.4 m L of cesium oleate precursor.After allowing the reaction to proceed for 5 s,immediate cooling is achieved using an ice-water bath.Subsequently,well-dispersed quantum dot solutions are obtained through high-speed centrifugation.Throughout the synthesis process,quantum dots with different doping concentrations （Al/Pb molar ratios of 0∶1,1∶2,1∶1,2∶3,and 3∶2） are synthesized by controlling the amount of aluminum bromide added.Results and Discussions The prepared Al∶Cs Pb Br₃ quantum dots can maintain the crystal structure of Cs Pb Br₃ quantum dots within a specific concentration range of Al³⁺ions,successfully introducing the energy level of Al³⁺ions.The addition of Al³⁺ions enhances the interaction of Pb—Br bonds in Cs Pb Br₃ quantum dots and significantly improves their stability（Fig.2）.Notably,while maintaining the crystal morphology of Cs Pb Br₃ quantum dots,Al∶Cs Pb Br₃ quantum dots exhibit reduced size and improved size uniformity.This is due to the substitution of larger Pb²⁺ions by smaller Al³⁺ions （Fig.3）.Furthermore,fluorescence and absorption spectral analysis reveals that Al³⁺ions effectively enhance the optical properties of Cs Pb Br₃ quantum dots,significantly increasing their fluorescence intensity.Importantly,Cs Pb Br₃ quantum dots and Al∶Cs Pb Br₃ quantum dots exhibit the same emission linewidth and demonstrate good environmental stability （Fig.5）.These improvements broaden the potential applications of Al∶Cs Pb Br₃ quantum dots across various fields.Conclusions In the paper,we successfully prepare Al∶Cs Pb Br₃ quantum dots using a hot injection method and comprehensively investigate the influence of Al³⁺ions on the properties of Cs Pb Br₃ quantum dots.The results from fluorescence spectra and absorption spectra indicate an effective enhancement in the fluorescence intensity of the quantum dots.With an increasing Al/Pb ratio,both the fluorescence and absorption spectra of the quantum dots exhibit a blue shift.However,when the Al/Pb ratio reaches 3∶2,the emission and absorption wavelengths unexpectedly undergo a red shift.Combined with X-ray diffractometer （XRD） data,this suggests that while a small amount of Al³⁺ions improves the optical properties of Cs Pb Br₃ quantum dots,an excessive amount disrupts their crystal structure.X-ray photoelectron spectroscopy （XPS） data demonstrate that the introduction of Al³⁺ions shifts the Pb and Br energy levels of Cs Pb Br₃quantum dots towards higher binding energies,enhancing Pb—Br bond interaction and thereby improving stability.Moreover,single quantum dot excitation tests comparing Cs Pb Br₃ quantum dots and Al∶Cs Pb Br₃ quantum dots （Al/Pb molar ratio of 1∶1） reveal distinct fluorescence blinking characteristics.The g²（0） values suggest that Al∶Cs Pb Br₃quantum dots （Al/Pb molar ratio of 1∶1） demonstrate superior single-photon performance,attributed to the effective reduction in quantum dot size,improved size uniformity,and enhanced quantum confinement effects upon the introduction of Al³⁺ions.This study offers new experimental insights and methods for the preparation of perovskite quantum dots and the optimization of their quantum light source performance.更多还原