Optical Property Of A Microsized Single-crystalline MAPbI₃ Plate Under Pressure

In recent years,organic-inorganic hybrid metal halide perovskite gradually become outstanding materials in the field of photovoltaic cell.As one of them,Methylammonium lead iodide?MAPbI₃?material is widely researched because of long carrier diffusion length,high carrier density and large absorption coefficient.Moreover,it also has the advantage of the low production cost and the advantages of the rapid growth of power conversion efficiency.In this paper,by combining the diamond anvil compression technology and micro-nano optical characterization technology,a micro-sized MAPbI₃ single-crystalline plate is researched though photoluminescence?PL?spectra,optical absorption spectra and optical microscopic images under pressure,and pressure-induced crystal structure evolution process and optical properties were analyzed.This result helps us to understand the source of excellent optical properties of MAPbI₃ from the perspective of crystal structure,the following studies were mainly conducted:?1?The pressure-induced phase transitions of a micro-sized MAPbI₃single-crystalline plate are tracked by the absorption and PL spectra.A tetragonal-cubic phase transition is confirmed within 0.23 GPa to 0.46 GPa.Furthermore,the MAPbI₃ plate experiences an isostructural cubic phase transition from 3.02 GPa to 3.57 GPa.Then the sample enters the amorphous phase after 4.26GPa.?2?The change of electron band gap and absorption edge under pressure was analyzed by absorption spectra,and the pressure-induced metallization of MAPbI₃single-crystalline plate is also evaluated about 44.6 GPa through extrapolating the bandgap-pressure curve to the pressure axis.?3?By analyzing the evolution process of the PL peak and absorption edge of MAPbI₃ single-crystalline plate from 3.02 GPa to 3.90 GPa under the pressure,the unique mechanism of luminescence was found in the process of the coexistence of nonradiative high pressure cubic phase and low pressure cubic phase.A systematic study of optical properties of a micron-sized MAPbI₃single-crystalline plate sample under high pressure is helpful to further study of the optical properties of organic-inorganic hybrid perovskite materials.All above the results will provides a new method to tailor and optimize the emission properties of optoelectrical devices based on organic-inorganic hybrid perovskite materials.