Synthesis And Dynamics Of Lead-free Perovskite Luminescent Materials

With the continuous development of material science,the research of photoelectric materials is becoming more and more critical.Therefore,plenty of scientists are working hard on the invention of new photoelectric material.Perovskite materials has been widely concerned recently for their great performance on photoelectric conversion.Lead-based perovskite is the most mature direction of perovskites in the present for their remarkable photoelectric performance and well-behaved stability.However,lead-based perovskite has trouble industrializing due to the toxicity of lead element which would causing irreversible harm to environment.Therefore,more researchers are focusing on the discovery of lead-free perovskite.Herein,preparation methods and dynamic research of two different kinds of novel lead-free perovskite are presented.Firstly,the ultrafast dynamics of a zero-dimensional(0D)perovskite(C8H17NH3)6SnBr8(CSB-2)is reported.Tin element which has the similar chemical properties with lead for located in the same main group together.There have been a lot of researches about tin-based perovskites.However,on account of the fact that the divalent tin ion can be easily oxidized to tetravalent tin ion,the perovskite based on tin element always do badly on stability.So,we can infer that there is a huge lack of reports of high-performance air-stable tin-based perovskites.The common perovskites appear as three-dimensional.Lots of researches shows that the dimension of perovskite can be reduced by adding macromolecular organic cations in the three-dimensional framework.Low-dimensional perovskite can exhibit as two-dimensional,quasi-two-dimensional,one-dimensional or even zero-dimensional structure by adjusting the proportion of macromolecular organic cations.Previous studies have confirmed that reducing the dimension of perovskite can change the luminescence properties and stability of perovskite in many ways.Herein,A zero-dimensional(0D)yellow emissive tin bromide perovskite with near-unity photoluminescence quantum yield(PLQY)was synthesized.The ultrafast excited-state dynamics of the yellow emissive perovskite was investigated by using femtosecond transient absorption spectroscopy.A clear mechanism depicting the growth and decay pathways of STEs in the 0D assembly was provided.At last,we prepared a new inorganic double-ion-doped double perovskite with unique luminescent properties.Cs2NaInCl6 is a typical kind of double perovskite with stable three-dimensional framework.The properties and stability of the classical double perovskite can be easily changed by doping other cation in the basis of the intrinsic structure.In this paper,the double perovskite is rarely doped by two kinds of different cations to get switchable luminescence properties and fluorescence lifetime.The emission intensity and fluorescence lifetime of newly synthesized double perovskite Cs2AgxNa1-xSbyln1-yCl6 can could be changed by adjusting the ratio of doped-ion.The new double perovskite isn't only a thermodynamically stable product,but also produce white-emission under control which means promising candidate in the coming years.