Defects And Photoelectric Properties Of Inorganic Halogenated Double Perovskite Cs₂AgBiBr₆ Films

Organic-inorganic halogenated perovskite has been widely used in optoelectronic devices because of its excellent photoelectric properties,such as strong light absorption,carrier mobility,large carrier diffusion length and easy solution preparation.Inorganic halogenated double perovskite can not only solve the hidden danger of lead toxicity and instability in the air environment,but also has excellent optical and electrical properties,making them suitable choices for high-performance,high-efficiency,and environment-friendly optoelectronic devices.In this paper,Cs₂AgBiBr₆thin films in inorganic halogenated double perovskite materials are selected as the research object,and the effects of the morphology,crystalline phase and defects of the thin films obtained by solution method on the optical and electrical properties are systematically studied.The effects of different modified layers on the resistivity of Cs₂AgBiBr₆thin films are further compared,and the mechanism is analyzed.The details are as follows:Cs₂AgBiBr₆crystalline particles were obtained by antisolvent precipitation method.Cs₂AgBiBr₆thin films were prepared by redissolving and spin-coating.The crystal phase structure,morphology,components and defect types of the films annealed at different temperatures were compared and analyzed.Combined with PL spectra,the electron transition mechanism related to film defects was studied.The fluorescence enhancement of thin films is attributed to the increase of V_Brdefects and the increase of the probability of composite luminescence.Cl element was introduced into the precursor solution,and Cl doped Cs₂AgBiBr₆was prepared by solution method.The effect of Cl^-on Cs₂AgBiBr₆defects was studied by comparing the changes of PL spectra under the ratio of Br^-and Cl^-.The results showed that Cl^-entering the Cs₂AgBiBr₆lattice reduced the covalent bond strength formed between Ag⁺ions and Bi⁺ions and halogen anions,and weakened the binding ability to Ag,As the density of states of Ag_idefects increases,the fluorescence enhancement of the films after Cl^-doping is attributed to the increase of transition probability related to Ag_ienergy level.ITO/AlO_x/Cs₂AgBiBr₆/PMMA/In structure device was designed and fabricated,The influence of AlO_xmodified layer on the resistance variation performance of the device is studied,and the mechanism of the resistance jump phenomenon was revealed.The research points out that the interface interaction between AlO_xlayer and Cs₂AgBiBr₆film enhances the adhesion between the film and the substrate,improves the surface compactness and uniformity of Cs₂AgBiBr₆film,and the thin AlO_xlayer plays the role of electron tunneling,The fitting results of I-V curve and temperature resistance curve show that the resistance transition behavior of the device is attributed to the formation and fracture of V_Brconductive filaments.