Nonlinear Optical Properties Of Lead Halide Perovskite And Its Application In Optical Limiting

Due to its unique and excellent photophysical properties,lead halide perovskite has been widely used in photoelectric devices such as photodetectors,light-emitting diodes,solar cells and lasers.In recent years,it has been found that lead halide perovskite also shows excellent properties in nonlinear optics（NLO）,including saturation absorption,two-or multi-photon absorption and nonlinear refraction.It is believed that perovskites will be serious nonlinear optical materials in the future.The nonlinear optical devices prepared from perovskites on the basis of their optical nonlinearity may open up a new viewpoint for the application of information and communication technology.In this paper,the nonlinear optical properties of three different lead halide perovskite quantum dots are studied,and the internal mechanism of their nonlinear optical phenomena is analyzed.Then,the most suitable quantum dots material,Cs Pb Br₃ quantum dots,was combined with antimony（Sb）to form a composite material by laser ablation in liquid phase（LAL）,which improved the nonlinear absorption ability.Finally,it was successfully added into solid matrix to realize its application in the field of optical limiting.The specific research contents are as follows:（1）Three kinds of Cs Pb X₃ quantum dots with different halogen ions were prepared by hot-injection method.Their structures,morphologies and basic optical properties were characterized,and their nonlinear optical properties were studied by Z-scan technique.Z-scan experiments were carried out with 532 nm,800 nm and 1064 nm laser respectively,and the mechanism of nonlinear absorption phenomena were analyzed.And the influence of the stability of the material itself and optical band gap on the nonlinear absorption were analyzed.Among them,Cs Pb Br₃ quantum dots have the strongest two-photon absorption capacity,and finally it is determined that Cs Pb Br₃ quantum dot have the potential of optical limiting.（2）Two kinds of optical limiting materials are combined to achieve coordination and optimization of different optical limiting mechanisms to improve optical limiting performance.By LAL method,antimony block was ablated in Cs Pb Br₃ quantum dots solution by 1064 nm pulsed laser.Different ablation time was controlled to obtain different color Cs Pb Br₃/Sb composite solution.The structure,morphology and basic optical properties of the composite structure were characterized and the formation mechanism of the composite structure was analyzed.Then,the nonlinear absorption properties were studied by Z-scanning.For the sample with ablation time of 1 h,the saturated absorption effect dominated at low light intensity,while the reverse-saturated absorption effect dominated at high light intensity,and the reverse-saturated absorption ability increased greatly.The results show that the sample can be applied to the field of optical limiting.（3）In order to overcome the limitation of solution materials in practical application,in this paper,optical limiting nanomaterials were successfully added into polystyrene（PS）matrix by direct blending method to produce round transparent plastic.The results show that they still have excellent optical limiting effect in solid matrix,and its optical limiting ability increases with the increase of the content of materials in PS matrix,which improves the practicability of its optical limiting application.The above results provide experimental and theoretical basis for the nonlinear optical research of lead halide perovskite and broaden its application in the field of nonlinear optical limiting.