The Effect Of Ion Doping On The Luminescence Of CH₃NH₃PbBr₃ Quantum Dots

In recent years,halide perovskite quantum dots?QDs?have attracted great attention due to their excellent optical properties and easy synthesis methods.So far,people have made many breakthroughs in improving the quantum yield and stability of the dots.Recently,tuning the photoluminescence by adding a new emission peak in the halide perovskite quantum dots structure have been significance reported by using the ion doping methods.However,there are some limitations to the selection of doped ions.In this paper,two different types of ions are used to dope methylammonium lead bromide?MAPbBr₃?QDs,aiming to study the change of luminescence properties upon doping.In addition,the effect of halogen ions on the QDs luminescence properties is also studied.The main research content includes the following three parts:?1?The effect of Eu doping on the luminescence properties of MAPbBr₃ QDs.We used a ligand-assisted reprecipitation strategy to fabricate MAPbBr₃ QDs and doped them with rare earth element Eu at room temperature.XRD,TEM and photoluminescence spectra indicate the incorporation of Eu²⁺into the MAPbBr₃ QDs lattices.Eu²⁺-doped MAPbBr₃ QDs shows a characteristic cubic structure very similar to the undoped QDs,and the morphology of doped and undoped QDs exhibit a spherical shape with a narrow size distribution.The photoluminescence spectra show that upon introducing Eu²⁺,there is new emission band appearing,and with Eu²⁺concentration increasing,such emission suppresses the original QDs emission,it proved that the energy transfers from MAPbBr₃QDs to Eu²⁺ions.?2?The effect of transition metal element doping on the luminescence properties of MAPbBr₃ QDs.We found that,the low bond dissociation energy of transition metals compounds,such as Mn Ac₂ were successfully doping into the QDs lattice.After doping,the QDs not only add a new emission peak but also still maintain the cubic structure.The new emission peak belongs to the transition metal d-d electron transition.?3?Effect of excess Br^-on the luminescence properties of MAPbBr₃ QDs.In the previous works,we confirmed the low bond dissociation energy of transition metals compounds were successfully doping into the MAPbBr₃ QDs,but when selected the high bond dissociation energy of transition metals compounds?MBr₂?,the doping failed.However,for the high bond dissociation energy of transition metals compounds?MBr₂?,it can be introduced more Br^-into the MAPbBr₃ QDs surface.The XPS and photoluminescence results show that excess Br^-can passivate the surface traps of MAPbBr₃ QDs,reduce non-radiative recombination,accelerate the electron transfer rate,and thus enhance CH₃NH₃PbBr₃ QDs photoluminescence intensity.