Structure And Fluorescence Characteristics Of Eu³⁺/Yb³⁺ Ion-doped CsPbCl₃ Quantum Dots Under High Pressure

Halide perovskite quantum dots have potential applications in optoelectronic devices due to their tunable band gap,excellent conversion efficiency and high photoluminescence quantum yield.As we all know,high-pressure technology can purely adjust the crystal structure of the compound without introducing impurities.Nowadays,high pressure technology has been widely used to explore the mechanism of changes in physical and chemical properties of materials under high pressure.Scientists have discovered new materials and new phenomena that cannot be obtained by traditional methods using high-pressure methods.The high-pressure study of halide perovskites has attracted increasing attention.These studies found that pressure can adjust the band gap and induce luminescence,discoloration and metallization.Doping as an effective method to improve the properties of materials is widely used in the study of perovskite halide materials.For the lanthanide ions doped CsPbCl₃ NCs,high photoluminescence quantum yield?QY?and stable and widely tunable multicolor emissions spanning from visible to near-infrared?NIR?regions are successfully obtained.At present,there are few reports on the high-pressure fluorescence characteristics of lanthanide ion-doped halide perovskite quantum dots.Therefore,here we used in-situ high-pressure experimental techniques to study the structural transition and fluorescence characteristics of Eu³⁺ions doped cubic phase CsPbCl₃ quantum dots,and explored the relationship between its structure and fluorescence characteristics.At the same time,we studied the phase transition of Yb³⁺ions doped cubic phase CsPbCl₃ quantum dots.The results of this paper are as follows:1.We studied the cubic phase CsPbCl₃ quantum dots doped with Eu³⁺ions under high pressure for the first time.It was found that the structural transition from cubic phase to cubic phase occurred at 1.53 GPa,and the luminescence of CsPbCl₃ host disappeared at 1.4 GPa.Our analysis showed that this was due to the Pb-Cl bond length shrinking and the[PbCl₆]^4-octahedral rotation and tilting with increasing pressure.2.We found that the luminescence of Eu³⁺ions was not affected by the structural changes of the matrix CsPbCl₃ QDs.The 5 PL peaks corresponding to the⁵D₀?⁷F_J?J=0,1,2,3,and 4?energy transitions of Eu³⁺ions did not shift or disappear significantly with increasing pressure.Due to the unique electronic layer structure of Eu³⁺ions,its luminescence remains stable under pressure up to 22GPa.3.Finally,we investigated the structural changes of Yb³⁺ions doped cubic phase CsPbCl₃ QDs under high pressure,and found that Yb³⁺ions doped CsPbCl₃ QDs underwent a cubic to cubic phase transformation under high pressure.The process was similar to Eu³⁺ions doped CsPbCl₃ QDs,but the change point was increased slightly,which may be caused by the different doping ion radius.