The Luminescent Properties Of Spectral Tunable Multicomponent Halide Perovskite

In recent years,lead halide perovskite（APb X₃）have attracted much attention from researchers due to their excellent optoelectronic properties such as tunable emission wavelength（400-700 nm）,high photoluminescence quantum yield,high carrier mobility and high defect tolerance.However,the progress of commercialisation of APb X₃ has been hampered by two key issues,namely structural instability and the toxicity of Pb.Therefore,it is meaningful to find suitable methods to improve stability and reduce the Pb content or replace it.In this thesis,low lead nano-riveted structured dual-emission perovskite were prepared by ion sharing;lead-free dual-emission perovskite were prepared by ion doping;additional luminescence center was introduced by further ion doping to achieve multi-color emission and effectively improve the optical properties.By utilizing the strategy of shared ion,Cs Pb X₃（X=Br,I）nanoparticles were nanocrystally interfaced onto CsSrAl₂O₄:Eu²⁺,Dy³⁺matrix,which not only improved the stability of perovskite but also greatly reduced the percentage content of Pb.The Cs Pb X₃/CsSrAl₂O₄:Eu²⁺,Dy³⁺nanocrystalline interface perovskite showed tunable dual-band emission both under light excitation and afterglow.Spectrally tunable white-light LED devices and flexible electroluminescent devices were fabricated using its characteristics and still exhibited dual-wavelength emission even after the excitation was removed.The prepared luminescent devices can store energy using natural light.Applications were designed for optical anti-counterfeiting by using multi-color,different excitations,and multiple time phases.By using a solution method to co-dope Sb³⁺and Ag⁺into Cs₂Na In Cl₆ perovskite,non-radiative recombination was achieved by breaking the transition forbidden effect through changing the electronic band structure.The optical properties of Cs₂Na In Cl₆were improved by the co-doping of Sb³⁺and Ag⁺,exhibiting efficient dual-band emission.By measuring the photoluminescence excitation spectra and fitting the emission peak intensity,peak energy,full width at half maximum and fluorescence lifetime related to temperature-dependent photoluminescence spectra,the essence of its dual-band emission was systematically studied.Sb³⁺doping provided[Sb Cl₆]^3-self-trapped exciton with high-energy emission,while Ag⁺doping not only induced the formation of[Sb Cl₆]^3-sub-band but also provided STE yellow emission band.Tunable white-light LED devices based on single material were fabricated utilizing the dual-band emission.Introducing ions is an effective measure to achieve multi-emission centers in lead-free perovskite.Furthermore,by introducing Cr³⁺ions into Cs₂Na_0.6Ag_0.4In Cl₆:Sb,near-infrared emission was achieved.Introducing luminescent center ions effectively transferred energy from the intrinsic level of the host of perovskite doped with Cr³⁺ions.To compensate for the red emission component,Mn²⁺was further introduced,realizing full-spectrum emission.Its color coordinates were tunable within the range of（0.27,0.26）and（0.45,0.41）by doping concentration.Cs₂Na_0.6Ag_0.4In_1-xCr_xCl₆:Sb had a red-shift in absorption after introducing Mn²⁺,overlapping with Cr³⁺emission and enhancing near-infrared emission.Mn²⁺not only provided emission center but also acted as a sensitizer.The luminescence mechanism and energy transfer mechanism were studied through fluorescence lifetime analysis and fitting of temperature-dependent photoluminescence.