Study On The Photophysical Properties And Preparation Of Inorganic CsPbBr₃ Perovskite Quantum Dots

Nanomaterials exhibit many interesting optoelectronic properties and show great potential for application in the field of light trapping and light emitting devices.With the development of nanomaterials,people have opened a special window to understand the world.In recent years,perovskite materials are becoming a new type of super-semiconductor with excellent photoelectric properties,which has wide application potential in the fields of illumination,laser,photon detection and photovoltaic.In 2009,Kojima's research group produced photovoltaic solar cells with CH₃NH₃PbX₃ as the anode material for the first time.In 2012,Mercouri G.Kanatzidi's group and HenryJ.Snaith's group used CsSnI₃ and CH₃NH₃PbI₃ to prepare high-efficiency solar cells,which led to the development of perovskite solar cells.Driven by the success of perovskite solar cells,researchers gradually explored the trihalogen perovskites.At the beginning of 2015,Kovalenko and his collaborators successfully produced quantum yields?⁹0%?for the first time.The full-inorganic perovskite NCs with a full-width half-width?10⁴0 nm?and size?4¹5 nm?fluorescence peaks can cover the entire visible light region.Following they report,CsPbX₃?X=Cl,Br,I?NCs have made remarkable progress in liquid phase synthesis chemistry,optoelectronic properties and their related applications.In order to further improve the application potential of optoelectronic devices based on perovskite NCs,carrier kinetics is one of the most important research areas for semiconductor NCs.However,current understanding of carrier kinetics of perovskite nano-films is still limited and need to explore further.This paper uses CsPbBr₃ NCs as an example because it has a non-crystalline structure and the corresponding photophysical properties have some differences between bulky films and isolated nanocrystals.Transient grating?TG?technology is a nonlinear time-resolved spectroscopy technique.The change of TG signal in semiconductor films depends on carrier diffusion and carrier number.Normal transient absorption spectra can only reveal information on changes in the number of carriers.TG spectroscopy can provide complex information about carrier dynamics and carrier kinetics in amorphous crystalline perovskite NC films,thus providing a more in-depth understanding of the properties of all inorganic perovskite nanocrystals.In this article,quantum dots and their basic properties were introduced at the beginning,followed by a brief introduction to the synthesis of perovskite materials and the use of inorganic perovskite NCs.We synthesized CsPbBr₃ NCs and CsPbI₃NCs by high temperature heat injection method.To illustrate the ionic crystals,we used ion exchange method to synthesize CsPbBr_1.5I_1.5 NCs.The method of basic characterization of nanomaterials was introduced,and the physical properties of CsPbX₃?X=Br,I,Br/I?were studied.Transient light-biased transient grating technology was used to study the carrier dynamics in CsPbBr₃ NCs films.The concentration of initial carriers and non-equilibrium carriers in nanocrystals is controlled by the pump light and the bias light,respectively.Analyzing the corresponding TG dynamics,it can be concluded that the recombination and diffusion of carriers can be effectively regulated by pump light and bias light.