High Pressure Study On One-Dimensional Lead-Free Organic-Inorganic Hybrid Perovskite C₄N₂H₁₄SnBr₄

Metal halide perovskites?MHPs?,a new type of photoelectric materials,have been widely studied by scientists because of its excellent physical and chemical properties.Up to now,the photoelectric conversion efficiency of solar cells certified by the national renewable energy laboratory has increased to 25%,and the photoelectric conversion efficiency of solar cells has increased rapidly in recent years.Especially in recent years,low-dimensional MHPs have been widely concerned and become one of the most popular optoelectronic materials.Low dimensional MHPs have the advantages of high stability,photoelectric and electronic tunability,and organic cation tenability etc.Moreover,because of the manipulation of organic components,metal halide perovskite has realized a variety of band structure control and color adjustment,and has shown ultra-high photoluminescence quantum yield?PLQY?,which also shows a great prospect in the application of optical devices.One dimensional?1D?MHPs have a unique structural characteristic.The metal halide octahedron form a line surrounded by organic cations through angular sharing,edge sharing or surface sharing.Their configurations can be linear or serrated,and the chemical formulas vary depending on the type of connection and the organic cation selected.The phenomenon known as self-trapping exciton?STE?is due to exciton-phonon interaction and is strictly dependent on the dimension of a crystal system.In the case of arbitrary exciton-phonon interaction intensity,the dimension of MHPs is reduced to 1D,and the results show that exciton is more prone to STE,resulting in many novel phenomena.Pressure,as an independent thermodynamic parameter,is a good way to change the structure.Using mature technology and a variety of experiment method for high pressure research,which not only helps to explore the perovskite the intrinsic relationship between architecture and nature,also helps to provide better research idea to find more excellent and new photoelectric materials.Here,we systemically investigated the relationship between the structure and optical properties of 1D perovskite C₄N₂H₁₄SnBr₄ under high pressure.Interestingly,we achieve an unexpected emission in intrinsically non-emissive 1D perovskite C₄N₂H₁₄SnBr₄ by high-pressure processing.This exotic pressure-induced emission?PIE?was believed to be greatly related to the large distortion of[SnBr₆]^4-octahedral motifs as a result of structural phase transition from monoclinic to triclinic.In situ high-pressure experiments,including PL,absorption,and angle-dispersive X-ray diffraction spectra?ADXRD?,were conducted to investigate the comprehensive pressure response of C₄N₂H₁₄SnBr₄.First-principles calculations corroborate that the enhanced transition dipole moment and the increased binding energy of self-trapped excitons?STEs?are highly responsible for the observed PIE.The work indicates that pressure processing gives us an effective mean to tailor low dimensional perovskite with enhanced functional properties.