Controllable Construction Of Cs₂AgBiCl₆/graphene And Its Electron Transfer

Double perovskites have shown great potential for solving the problem of toxic and unstable lead halide perovskites in practical applications.High quality Cs₂AgBiCl₆double perovskites nanocrystals（NCs）,an indirect bandgap semiconductor with a bandgap of 2.35 e V,were prepared using TMS-X（X=Cl,Br,I）thermal injection method.The Cs₂AgBiCl₆ NCs have an emission linewidth of 12-105 nm and a photoluminescence（PL）lifetime of 5.7-20.8 ns.In addition,several synthetic experiments were carried out on Cs₂AgBiCl₆ NCs using different ligand ratios,and a certain degree of morphological control was initially achieved.Using laser excitation at 405 nm,the variable temperature spectrum in the cryogenic region was measured against Cs₂AgBiCl₆ NCs The emission peak of Cs₂AgBiCl₆ NCs was 676 nm at 80 K.The emission peak shifted blue with increasing temperature to 640 nm at 280 K.To accelerate the charge separation and transfer of Cs₂AgBiCl₆ NCs materials,novel functionalized Cs₂AgBiCl₆/reduced graphene oxides（r GO）nanocomposites were synthesized by growing Cs₂AgBiCl₆ NCs in situ on two-dimensional graphene oxides（GO）nanosheets.The Cs₂AgBiCl₆/r GO nanocomposites were compared with pure Cs₂AgBiCl₆ NCs using transmission electron microscopy（TEM）characterization,X-ray diffractometer technique（XRD）,absorption spectroscopy,and steady/transient fluorescence spectroscopy.The Cs₂AgBiCl₆/r GO nanocomposites exhibited significant PL bursts and shorter PL decay lifetimes compared to pure Cs₂AgBiCl₆ NCs.The fluorescence lifetime of Cs₂AgBiCl₆/r GO nanocomposites undergoes different degrees of decay with the addition of different masses of GO.The mechanism of PL quenching after the addition of graphene is explained and the fluorescence burst is attributed to photoexcited charge transfer.This composite has good prospects for optoelectronic applications such as photodetectors and photocatalysts.