Preparation And Luminescence Properties Of Lead-Free Halide Double Perovskite Phosphors

With the continuous improvement of human demand for lighting,the traditional incandescent lamp due to high energy consumption,easy to damage,has been difficult to meet the human demand for lighting,and the emergence of LED lamp,greatly changed the status of human lighting.Compared with the traditional light source,the energy consumption of LED lamp is only 1/10 of that of incandescent lamp and 1/4 of that of energy-saving lamp;Secondly,LED lamp does not contain mercury and other harmful substances,in line with the concept of environmental protection.At present,the technology of phosphor conversion LED has become mature,but due to the lack of warm color light,most of the white light devices emit cold light.Therefore,it is of great significance to study efficient and stable warm color phosphors,and it is necessary to invest more energy.The existing research shows that double perovskite has three-dimensional electron dimension,excellent physical and optoelectronic properties,such as environmental stability and tunable band gap.It is a good absorption material for photovoltaic applications.It has great potential in the future application of w-LEDs.This paper mainly includes the following three aspects:(1)A series of novel double perovskite phosphors Cs2AgInCl6:Na+,Tb3+were synthesized by hydrothermal method.All the phosphors are cubic phase system with Fm3m space group.The sample can be excited by 350 nm excitation,and the strongest emission peak appears at 560 nm.The results of thermal stability show that when the temperature rises to 100?,the fluorescence intensity decreases to 51%of the initial value.Under the optimum doping condition,the Photoluminescence quantum yield of Cs2Ag0.6Na0.4In0.8Tb0.2Cl6 phosphor is 14.23%,and the color coordinates are(0.4067,0.4873).(2)A series of Cs2NaBiCl6:Mn2+ phosphors were prepared by liquid phase synthesis under the excitation of ?ex=356nm,the strong emission peak is around 580 nm,which is attributed to the 4T1?6A1 level transition in Mn2+.The samples were analyzed by X-ray photoelectron spectroscopy.The results show that the transition metal Mn2+ is effectively doped into the matrix Cs2NaBiCl6.When n(Mn)/n(Bi)=0.7,it is the best doping amount of transition metal Mn2+,and Cs2NaBiCl6:Mn2+ has higher luminescence intensity,and the color coordinates are(0.5089,0.4840).(3)A series of Cs2NaBi1-xCl6:xEu3+orange red phosphors were prepared by hydrothermal method.The crystal structure analysis shows that Eu3+is successfully doped into Cs2NaBiCl6 structure and becomes a good luminescent center.The emission spectra show that there is a strong orange red emission at 610 nm under 365 nm UV excitation,which corresponds to the 5D0?7F2 level transition of Eu3+.With the change of Eu3+ doping concentration,the fluorescence intensity reaches the maximum when the doping concentration x=0.05.The results of the thermal stability of the phosphors show that the fluorescence properties of the phosphors begin to decay obviously when the temperature is higher than 100?,which indicates that the phosphors have high thermal stability in the test range.