Stability And Stimulated Emission Of CsPbBr₃ Perovskite Films

Perovskite materials have a wide range of applications due to their excellent optoelectric properties.The preparation of perovskite materials with excellent photoelectric properties,safety and stability is the key to the development of perovskite based optoelectric devices.CsPbBr₃,as the representative of inorganic lead halide perovskites,has the advantages of low nonradiative loss and high optical gain.However,the poor photoluminescence performance,especially the short carrier lifetime,of the solution-processed CsPbBr₃ films,limits the stimulated emission under continuous wave pumping.In addition,the poor stability under atmospheric conditions is also difficult to meet the actual application needs.In this thesis,inorganic CsPbBr₃perovskite was studied,and perovskite films with excellent luminescent properties and stability were prepared by organic ligand incorporation and surface/interface modification.The surface morphology,luminescent properties,stimulated radiation properties and air stability of the films were studied.The main contents of this thesis are as follows:1.Low dimensional OA₂Cs_n-1Pb_nBr_3n+1 perovskite films have been successfully prepared by one-step spin coating method with perovskite precursor solution added with long chain cations of ammonium?OA?.After the characterization of microstructure and structure,we found that the film has super smooth,compact surface morphology and good crystallization performance.Photoluminescence characterization showed that the film appeared band edge emission at 520 nm.2.In order to improve the luminescent properties of perovskite films,a method of surface/interface modification was proposed.After substrate pretreatment and surface passivation,the carrier lifetime of the films increased from 3.1 ns to 44 ns.At the same time,by introducing a mixed polymer layer on the surface of perovskite film,combined with the surface passivation effect and symmetrical waveguide effect,the net gain coefficient of the film reaches 694 cm^-1,showing the potential of strong light amplification.The lifetime and gain coefficient are higher than the reported value of inorganic lead halide perovskite.3.The perovskite films with high air stability have been successfully prepared by combining low dimensional perovskite structure design and substrate selection.In the atmospheric environment with 55%average relative humidity,the stability of the film without encapsulation was more than 8 months,and the influence of perovskite structure,substrate and interface passivation on the stability of the film in the atmospheric environment was systematically studied by tracing the micro morphology,crystal structure,luminescence characteristics and stimulated emission characteristics of the film for up to 8 months.It is found that the high stability film benefits from the lower point defect density of the film,thus inhibiting the degradation of perovskite under high humidity.