Synthesis And Carrier Dynamics Of New Inorganic Perovskite Nanocrystals

As people’s demand for energy is getting higher and higher,traditional fossil energy has begun to gradually fail to meet people’s requirements.Therefore,people have be-gun to turn their attention to new types of clean energy.Therefore,new types of clean energy such as solar cells have been invented by people.In recent years,perov-skite materials have been found to have excellent performance and promise in the fields of solar cells,photodetectors,electroluminescence devices,etc.,and have attracted the attention of researchers all over the world.This article mainly studies new perovskite materials from two points.The first point is to improve the synthesis scheme,improve synthesis conditions,and increase synthesis methods to synthesize new,low-toxic,high-performance calcium based on the previous research of other researchers.Titanium ore nanocrystals,and characterize and study its stability,photoelectric properties and other aspects.On the other hand,it is to study the behavior of hot carriers from the aspect of microscopic dynamics,and try to clarify its influence on luminescence and power generation performance,and use this to develop new perovskite materials.This article first synthesized a series of alloyed non-lead halide double perovskite Cs2AgBi1-xSbxBr6(0≤x≤0.75)nanocrystals on the basis of previous literature,and performed X-ray powder diffraction measurement on them.It was confirmed that it was a pure cubic structure,and the structure was not changed after doping with Sb,which was also confirmed by subsequent transmission electron microscopy measure-ments.Then we measured its steady-state absorption spectrum,and calculated the band gap of double perovskite Cs2AgBi1-xSbxBr6(0≤x≤0.75)nanocrystals through its steady-state absorption spectrum,and found that with the proportion of Sb element With increasing,the band gap of Cs2AgBi1-xSbxBr6(x=0.25,0.5 and 0.75)nano-crystals becomes slightly smaller.Finally,we measured the transient absorption spec-trum to study the difference in hot carrier dynamics,calculated the absorption cross section σ,and found that its value has a linear relationship with the Bi element con-tent.Subsequently,by fitting the ground state bleaching(GSB)attenuation signal,we found that the proportion of the carrier trapping process increases with the increase of Sb content,while the probability of exciton recombination decreases with the increase of Sb content.It is the defect state-mediated carrier recombination that occupies the main position.Finally,I can come to the conclusion that we can adjust the selftrapp-ing state(STE)absorption by adding new trivalent metal elements,adjusting the ratio of the trivalent metal elements,and making the non-lead halide double perovskite of the trivalent metal alloy.It provides a new idea for the subsequent research on the new high-performance non-lead halide alloy double perovskite.In the third part of this paper,a new type of alloyed CsPb1-xYbxI3 colloidal quantum dots doped with rare earth Yb2+ is synthesized.And through X-ray diffraction spectro-scopy and transmission electron microscopy,it has been confirmed that it has a new type of crystal structure,which is different from the cubic structure of the traditional α-CsPbI3 perovskite quantum dots.Its absorption spectrum proves this.The synthe-sized CsPb0.4Yb0.6I3 quantum dots have a fluorescence peak at about 450 nm,and have a quantum yield close to unity.Then we compared it with pure CsPbI3 perovskite quantum dots and tested the stability.CsPb0.4Yb0.6I3 quantum dots can be stored in the atmosphere for more than five months without XRD change,and its fluorescence brightness is also There was no change under visual observation.And under the baking temperature of 80 degrees,the CsPb0.4 Yb0.6I3 quantum dots can persist for several hours without significant decrease in fluorescence intensity.Subsequently,the femtosecond transient absorption spectroscopy was used to compare the dynamic differrence between CsPbI3 perovskite quantum dots and CsPb0.4Yb0.6I3 quantum dots,and the ground state bleaching signal of CsPb0.4Yb0.6I3 quantum dots was more insen-sitive to the pump flux.And the hot carrier relaxation speed of CsPb0.4Yb0.6I3 quantum dots is much faster than that of CsPbI3 quantum dots.