Giant enhancement of photoluminescence quantum yield in 2D perovskite thin microplates by graphene encapsulation  

作　　者：Wancai Li Jiaqi Ma Xue Cheng Dehui Li 

机构地区：[1]School of Optical and Electronic Information,Huazhong University of Science and Technology,Wuhan,430074,China [2]Wuhan National Laboratory for Optoelectronics,Huazhong University of Science and Technology,Wuhan,430074,China

出　　处：《Nano Research》2021年第6期1980-1984,共5页纳米研究（英文版）

基　　金：the support from the National Basic Research Program of China(No.2018YFA0704403);the National Natural Science Foundation of China(No.61674060)。

摘　　要：The optoelectronic performances of the layered materials are strongly dependent on the thickness of the samples due to the surface effect.As the size of the samples decreases to few nanometers,the surface depletion field and surface defect density are prominent arising from the large surface to volume ratio.For instance,thin two-dimensional(2D)organic-inorganic hybrid perovskite microplates usually exhibit a rather low photoluminescence quantum yield(PLQY),owning to the strong surface effect.Here,we report that the PLQY can be enhanced as large as 28 times in(iso-BA)2Pbl4(BA=C4H9NH3)2D perovskite thin microplates encapsulated by graphene,resulting in that the PLQY is more than 18%for the microplate with a thickness of 6.7 nm at 78 K.As the thickness of the 2D perovskite microplate increases,the enhancement is gradually reduced and finally vanishes.This observation is in striking contrast to that in monolayer transition metal dichalcogenides(TMDs),when the PLQY is quenched by covering a layer of graphene due to the efficient charge transfer.The enhancement of PLQY in 2D perovskites can be mainly ascribed to the reduced quantum confined Stark effect(QCSE)due to the reduced surface depletion field after covering graphene flake,resulting in the enhanced radiative recombination efficiency.Our findings provide a cost-effective approach to enhance the luminescence,which may pave the way toward high performance light emitting devices based on 2D perovskites.

关 键 词：two-dimensional perovskite PHOTOLUMINESCENCE quantum yield quantum confinement surface depletion field 

分 类 号：TQ132.32[化学工程—无机化工]