High Stability Perovskite Nanoplate Laser Based On Lead Iodide Passivation

Lead halide perovskite materials because of its unique physical properties,including diffusion length is long,long life,high mobility of charge carriers,tunable wavelength(390-790 nm)and high absorption coefficient,the solar cell,detector,laser is widely used in the photoelectric device,however,and the material is heated by trap state density and large easy degradation and other issues,the influence of The stability of perovskite semiconductor materials still faces challenges,which restricts its further development.We use methylamine lead iodide perovskite nanosheets as the gain medium and optical resonator of the laser.As a single crystal,it has a much lower density of defect states than polycrystalline thin films,so it is a high-quality material for realizing high stability laser.Based on this,the laser irradiation stability of organic-inorganic perovskite in laser was studied.The main research contents of this paper include the following two aspects:1.Using two step perovskite nano chemical vapor deposition),by adjusting the gas flow velocity in the process of preparation in order to control the content of iodide in perovskite found perovskite in the presence of moderate lead iodide can effectively fill the holes of perovskite,have the effect of passivation,significantly reduced perovskite laser threshold,improve the quality factor(Q)and its stability.The innovation lies in that the lead iodide material is the raw material for the synthesis of perovskite.Compared with other passivators,it can effectively avoid the introduction of other components to affect the performance of the laser.The half-high full width(FWHM)of the passivated nanoplate laser is 0.2 nm,the corresponding Q value is as high as 3900,and the threshold is as low as 15.7μJ/cm2.Compared with the unpassivated nanoplate,the stability of the passivated Pb I2 nanoplate is improved from 1000 s to 4650 s(2.8×107 laser pulses).The stability of the passivated laser is 4.6 times that of the non-passivated one,which is much higher than the stability of all the MAPb I3 nanometer lasers reported at present(the stability of the highest MAPb I3 nanometer laser reported at present is 1.3×107 laser pulses).2.In view of the present perovskite materials under the condition of laser irradiation decomposition mechanism is not clear,perovskite materials was studied in the decomposition mechanism of laser irradiation conditions,mainly divides into decomposition and decompose step by step from the defect hole two kinds,be way of the degradation of nanometer sheet after passivation by degradation from point defect improvement for the passivation of degradation step by step.In order to further prove the improvement of stability,the pump source was increased from the initial femtosecond pulse to the picosecond pulse.Under the picosecond pulse,the excitation phenomenon of perovskite nanosheets was still observed.Under the picosecond pulse,the nanoplate can still stably excite 1.08×107 laser pulses.In conclusion,this paper proposes a strategy of Pb Iodide passivation of perovskite nanoplate lasers.By regulating the content of Pb I odide,the passivation and stability of the nanoplate defects are improved.In addition,two decomposition mechanisms of perovskite materials under the condition of laser irradiation decomposition from the defect hole and layer by layer decomposition,the performance of the nanoplate laser is better improved,laying a foundation for the realization of continuous and electrically pumped perovskite laser in the future.