Research On Controllable Synthesis And Optoelectronic Properties Of Halide Perovskite Nanocrystals Embedded In Polymer Composite Films

To achieve major strategic decisions of reach the CO₂ emission peak and carbon neutral,we must vigorously develop green energy,and solar energy is the preferred green energy.How to use the sun’s energy efficiently has always been a topic of research.Perovskite materials have become a hot spot in the field of solar cell research because of their high conversion efficiency.Perovskite materials also have excellent photoelectric properties,according to these properties,perovskite materials can also be used in light-emitting diodes,photodetectors,lasers and other fields.Perovskite materials have three disadvantages of being afraid of water,oxygen and heat.By introducing polymers,the stability of perovskite materials can be improved.Polyvinylidene fluoride（PVDF）composite films embedded with perovskite nanocrystals（NCs）can maintain their stability for a long time under extreme water,oxygen,and acid-alkali environments.This paper mainly studies the synthesis of PVDF composite films embedded with FAPbBr₃（FA=formamidinium）nanocrystals and their photophysical properties.By adjusting the reaction temperature to change the size of perovskite nanocrystals,and obtained polyvinylidene fluoride composite films embedded with FAPbBr₃nanocrystals synthesized under room temperature（#1）and 60^oC（#2）conditions,and then we studied the two composite films as follows:1.A series of characterizations were carried out on the synthesized two composite films,and the size and shape of perovskite nanocrystals in the two composite films were determined,the size of perovskite nanocrystals in#2 was greater than the size of#1,the phase of PVDF and the phase of perovskite in the composite film were determined,and the perovskite and polymer in#1 were more closely combined than#2.2.In terms of absolute fluorescence quantum yield,#2 is greater than#1.At 340K,the thermal stability of#2 is better than that of#1.After that,we made the corresponding photodetectors#1 and#2,and conducted I-V tests on both,and found that the photocurrent of#2 was stronger than the photocurrent of#1.In order to broaden the application of polyvinylidene fluoride composite films embedded with FAPbBr₃nanocrystals in the field of optoelectronics,a primitive flexible photodetector was prepared.Our results show that the film can be applied to many semiconductor devices.3.The relationship between photoelectric properties and carrier dynamics in composite films was analyzed in detail by transient absorption and temperature-dependent spectroscopy.The activation energy and phonon energy of both were extracted from the temperature-dependent emission spectrum.We extracted k₁,k₂ and k₃ of#1 and#2 based on transient absorption spectra.Through the analysis,the reason why the photoelectric performance of#2 is better than#1 is obtained.