Synthesis And Photoelectric Properties Of Metallic Lead-free Peroviskite Derivatives With Blue Emission

Lead halide perovskites have attracted great attention owing to their excellent photoelectric properties.However,the toxicity of the lead may limit its commercial value.The emergence of perovskite derivatives has solved the environmental stress caused by toxicity problems.Comparing with green and red perovskite LEDs,the blue-emitting perovskite devices termed as one of the three primary colors,are facing with a series of problems.such as a low fluorescence quantum yield,poor stability and short PL lifetime.Therefore,how to prepare high quality lead-free blue-emitting materials is the key to realize panchromatic display of perovskites in the future.In this paper,the optical properties of Sb-based and Cu-based perovskite derivative materials under different reaction conditions are studied.A highly blue emission material,Cs₃Sb₂Br₉,with a PL quantum yield of 63%and white emission material of Cs₃Cu₂I₅@Cs Cu₂I₃ with a PL lifetime of 18.63 ns were obtained.This paper mainly contains the following research contents:(i)Solvothermal method was used to prepare Cs₃Sb₂Br₉perovskite derivatives.The effects of different reaction time on the crystallinity and optical properties of Cs₃Sb₂Br₉perovskite derivatives was studied.According to the characterization results,it is found that the crystal size and crystallinity of Cs₃Sb₂Br₉ is enhanced and there is not red-shifts due to the larger size crystals were not acted on quantum confinement effect.Furthermore,the larger size of Cs₃Sb₂Br₉ crystal has low surface defects,with a longer PL lifetime and the maximum PL quantum yield of up to 63%.(ii)Hot injection and microwave synthesis method was used to prepare the Cs₃Cu₂Br₅perovskite derivatives.The properties of the materials prepared by the two methods were compared.Then,choosing the microwave synthesis method with simple operation and high repetition rate to prepare the Cs₃Cu₂Br₅ perovskite derivatives.The results show that the wide blue emitting originate from self-trapped excitons radiation recombination.Otherwise,the stability of the Cs₃Cu₂Br₅ material is greatly affected by the external environment.(iii)Blue emissive Cs₃Cu₂I₅ and yellow emissive Cs Cu₂I₃ were prepared by microwave synthesis method.According to exploring the experimental conditions,it is found that the materials of Cs₃Cu₂I₅@Cs Cu₂I₃ composed of the blue emissive Cs₃Cu₂I₅ and yellow emissive Cs Cu₂I₃.In addition,the PL lifetime up to 8.1 and 8.77 ns for Cs₃Cu₂I₅and Cs Cu₂I₃.Otherwise,the Cs₃Cu₂I₅@Cs Cu₂I₃ PL lifetime up to 18.63 ns.Finally,the Cs₃Cu₂I₅ material was used to fabricate LED devices with the maximum EQE was 0.01%.