Study On The Preparation Of CsPbBr₃ Thin Film By Co-evaporation Method And Its Photoelectric Properties

Since 2015,the excellent photoelectric properties of all-inorganic perovskite Cs Pb X₃(X=Cl,Br,I)have attracted great attention at home and abroad.Compared with organic-inorganic hybrid perovskite materials,the all-inorganic lead halide perovskite has better thermal stability,and the material has high exciton binding energy at room temperature,Free excitons are easy to combine with impurities to form a complex center,and exciton luminescence can be produced at room temperature.Studies have found that if the perovskite film has a smoother surface morphology and large-sized crystal grains,it can effectively reduce grain boundary scattering,further increase carrier mobility,and inhibit ion migration.Since the perovskite film itself has poor electrical conductivity,the research based on effectively increasing the grain size cannot be delayed.At present,most researchers control the grain size of thin films prepared based on the solution method.In this paper,we try to prepare Cs Pb Br₃thin film by thermal evaporation method,adjust the growth conditions,and perform rapid annealing treatment on the thin film.Finally,a high-quality Cs Pb Br₃thin film with an average grain size of 3?m is obtained.The main research contents and results of this article are as follows:In this paper,a co-evaporation method was used to prepare Cs Pb Br₃thin films,and methods to improve the grain size and crystal quality were explored,and a high-quality Cs Pb Br₃thin film with an average grain size of 3?m was obtained.The research content and main results of this article are as follows:(1)In this paper,Pb Br₂and Cs Br are used as precursors,and dual-source co-evaporation is used to prepare perovskite films.By precisely controlling the evaporation temperature,adjust the evaporation source rate ratio,the best conditions for film growth were explored.The study found that the evaporation rate ratio of Pb Br₂to Cs Br is 3:1,which was suitable for obtaining a relatively correct stoichiometric ratio,which verifies us the deposition technology accurately regulates the film growth conditions,and successfully prepared a high-purity Cs Pb Br₃film.(2)Characterizing and optimizing the surface morphology and crystalline quality of the perovskite layer is the key to improving the performance of the device.Therefore,in this paper,the optical properties and surface morphology of the film were measured by adjusting the substrate temperature and film thickness during the growth process.Characterization results show that increasing the substrate temperature and increasing the film thickness can indeed improve the crystalline quality and grain size of the film to a certain extent.When the substrate temperature is 150?and the film thickness is200 nm,the crystalline quality of the Cs Pb Br₃film and the surface shape of the film Looks best.(3)Study the effect of rapid annealing treatment on the crystalline quality and optical properties of Cs Pb Br₃thin films.By adjusting the annealing process,the annealing conditions are refined,and rapid annealing is carried out in the air atmosphere.Through the characterization of its optical properties and surface morphology,the optimal annealing temperature and annealing time were further explored.The study showed that the optimal annealing condition was annealled at 460?for 60 s,and finally obtained an average grain size of 3?m,without obvious Holes and defects,well-crystallized Cs Pb Br₃film.Figure 38,table 11,reference 59.