| Since 2009,organic-inorganic halide perovskite(OHP)has made a major breakthrough in the field of solar cells,which make perovskite semiconductor materials a focus and hot spot in the world.Due to their unique physical and chemical properties,such as wide spectrum range,high absorption coefficient,high carrier mobility,long carrier diffusion distance,shallow defect level and so forth,OHP had been a promising material to be utilized in light emitting display devices,solar photovoltaic cells and detectors.At present,the emerging all inorganic halide perovskite(IHP)can not only overcome the essential defects of OHP that organic molecules easily decomposing at high temperature,but also have the advantages of high luminous efficiency,easy tunable luminous wavelength,especially the half peak width of luminescence is very narrow,which make them a star material for luminescence and display devices.However,their intrinsic poor stability against the water and thermal greatly limits their practical applications.Focused on two core scientific issues,one is the macroscopic rapid preparation of all inorganic perovskite nanocrystals,and the other is improving the stability of the inorganic perovskite nanocrystals against water,heat and electron radiation,the research work are mainly concluded as follows:1)Reporting a general strategy based on microwave technique for the rapid production of low-dimensional all-inorganic CsPbBr3 perovskite nanocrystals.Through the exploration and optimization of the key parameters such as different proportions of oleic acid and oleylamine(9:1,8:2,4.5:6),concentration of PbBr2 precursors(2,1,1/2,1/3),microwave powers(100,400,600,800 W)as well as the irradiation times(1,3,5 min),realizing the controble growth of all-inorganic CsPbBr3 perovskite NCs with tunable dimensionalities from OD to 1D to 2D,and tunable size such as nanocubes from 8.1 to17.4 nm,nanorods from 31 to763 nm and nanosheets from 235.4 to 312.3 nm.2)An improved hot injection technique,namely microwave-assisted hot injection,for mass production of Mn2+-doped CsPbC13(Mn2+:CsPbCl3)perovskite nanocrystals was reported.This strategy exhibits the capacity for gram-scale synthesis of Mn2+:CsPbC13 NCs,and the PL quantum yelid(PL QY)up to 65%,which is the highest among the Mn2+-doped perovskite NCs ever reported.At the same time,Mn2+ doping have significantly enhance the thermal stability of the CsPbC13 NCs,the PL of nanocrystals with doping concentration of 6.5%remained almost unchanged during the temperature from 300 K to 380 k;3)Reporting a Mn2+ doping strategy for fundamentally improving the stability of metal-halide perovskite nanocrystals against e-beam irradiation.Study shows that the life time of Mn2+-doped NCs(with doping concentration of 6.5%)before complete structural damage caused by e-beam irradiation was 10-fold prolonged,in comparison to that of their pure analogue.The electronic band structure,charge density difference and formation energy was calculated by first-principles,which revealed that the incorporated Mn2+ dopants could bring stronger Mn-Cl and Pb-Cl bonds,as well as enlarged tolerance factor,and this is the essential reasons for the significant improvement of the stability of perovskite against electron irradiation;4)Based on electrostatic spinning technology,coaxial needle is adopted to realize the preparation of core-shell nanofibers with the shell layer is pure PS and the core layer is CsPbX3@PS.This unique structure,on the one hand,realizes the uniform in-situ growth of perovskite nanocrystals in polymer nano-fibers,achieving good dispersing and coating effect of perovskite nanocrystals;and at the same time realizes further coating of the nanocrystals exposed on the surface of the CsPbX3@PS layer.Results show that the PL QY is up to 45.7%,and could remain 90.5%and 84.2%after being immersed in water for 10 days and 180 days respectively.Indicating significantly enhanced stability against water of the perovskite NCs by coaxial structure. |
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