Pressure-Induced Structural Evolution And Photoelectric Properties Of One-Dimension Metal Halide Hybrid Perovskite

Metal halide perovskite is known as the"star material"and is a research hotspot in the fields of physics,optics,electronics and materials science.Among them,Organic-inorganic metal halide perovskite?OMHPs?has excellent photoelectric properties,so it has a promising future in photovoltaic and photoelectric fields.With the deepening of research,the power conversion efficiency?PCE?of OMHPs solar cells has quickly risen from 3.8%to 25.2%in just 9 years.Besides the rapid progress in solar cells,OMHPs have been explored for utilization in light-emitting diodes?LEDs?,photodetectors and optically pumped lasers.However,most of these materials do not emission at normal temperature and pressure,and have wide band gap,which hinder their further application.In addition,As an independent thermodynamic parameter,pressure can regulate the structure and properties of materials without changing their chemical composition.Increase the pressure can effectively shorten the distance between adjacent atoms,the electron orbital overlap degree increases.Pressure can provide an effective and important way to modify the crystal structures and properties of hybrid perovskites,research and development space can greatly expand the material science.Therefore,exploring the effect of high pressure on the structural stability and optical properties of organic inorganic hybrid perovskite is of great scientific significance and application value.As a typical one-dimensional metal halide hybrid perovskite,Ethylammonium lead iodide?C₂H₅NH₃PbI₃?with a unique one-dimensional structure analogous to quasi-one-dimensional quantum wires,is presented as a new organic-inorganic hybrid halide perovskite among the emerging photoactive materials.Because the dimension of one-dimensional material system is greatly reduced,its characteristics are obviously different from other material systems,and show many special phenomena.this paper used Diamond Anvil Cell?DAC?,combined with in situ high-pressure photoluminescence?PL?,UV–vis absorption,synchrotron X-ray diffraction?XRD?,and infrared experiments.Here we report that how pressure triggered the optical and structural properties of 1D hybrid perovskite C₂H₅NH₃PbI₃.The results are as follows:1?In situ high pressure IR spectra and synchrotron radiation X ray diffraction show that,at 3.2GPa,the rearrangement of the hydrogen bonding network and the transition of EA⁺organic cations from disordered to ordered,which led to asymmetric distortions of the PbI₆ units.These changes resulted in the crystal lattice began to transform into monoclinic phase.While increasing the pressure to 4.5GPa,the octahedral chain was seriously distorted under the traction of hydrogen bond?N-H···I?,which was enough to completely transform the ethylammonium lead iodide from the original orthogonal Pccn phase to the monoclinic p21/c phase.2?Achieve the shocky-queissen optimal band gap under low pressure.In situ high-pressure absorption spectroscopy experimental results show that,in the pressure range of 0-26.5GPa,C₂H₅NH₃PbI₃ absorption edge is red shifted and the bandgap continues to decrease.At about 24.7GPa,the bandgap of EAPbI₃ reaches the Shockley–Queisser optimum bandgap?1.34 eV?.3?Pressure induced double emission strength enhancement.In situ high-pressure fluorescence spectroscopy experimental results show that strong quantum confinement that generates double emission strength enhancement and give a 5-fold enhanced broadband jacinth light emission under pressure.The model of thermally activated trapping and de-trapping perfectly verified the reason for the two emission enhancement of 1D perovskites under pressure.Experimental data analysis indicates that the decrease in the conduction band energy caused by the shortening of the Pb-I bond length contribute to the first increase in emission intensity at2.7GPa.The second increase of emission intensity is triggered at 4.5GPa,induced by the increased self-trapping depth rooting in a strong coupling between distorted PbI6⁺octahedra and phononafter the phase transition from orthogonal phase to monoclinic phase.This work mainly investigate the structure and property changes of typical one-dimensional metal halide hybrid perovskite under high pressure,and reveals the structure-property relationship,which provides new strategies and ideas for the further design and preparation of new perovskite materials.