简便合成相可调的CsPbBr_(3)-Cs_(4)PbBr_(6)复合纳米晶及相转变过程的原位研究  

Facile synthesis of phase-adjustable CsPbBr_(3)-Cs_(4)PbBr_(6) composite nanocrystals and in-situ study of phase transformation process

作　　者：陈雪莲 申岩冰 袁芝聪 李恺瑞 潘喜强 Chen Xue-Lian;Shen Yan-Bing;Yuan Zhi-Cong;Li Kai-Rui;Pan Xi-Qiang(School of Materials Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China;College of Chemistry and Chemical Engineering,Xi’an Shiyou University,Xi’an 710065,China)

机构地区：[1]西安石油大学材料科学与工程学院,西安710065 [2]西安石油大学化学与化工学院,西安710065

出　　处：《物理学报》2024年第9期223-235,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62104191);西安石油大学研究生创新与实践能力培养计划(批准号:YCS23113077)资助的课题

摘　　要：通过改变四正辛基溴化铵(TOABr)用量和Cs/Pb摩尔比,在室温下采用一步单溶剂法成功制备出单斜相CsPbBr_(3)和六方相Cs_(4)PbBr_(6)两种相结构可调的钙钛矿纳米晶.研究发现,当TOABr浓度较低时(Cs/Pb/Br=1∶1∶4),体系中主要生成了单斜相的CsPbBr_(3)纳米立方块,该立方块主要经历了快速成核、尺寸分布聚焦生长和Ostwald熟化生长3个阶段,最终尺寸为(11.8±1.6)nm.随着TOABr用量的增加,Br^(-)与Pb^(2+)结合形成[PbBr_(3)]^(-)和少量的[PbBr_(4)]^(2-)络合物,两种络合物相互竞争.在成核期和生长早期体系中[PbBr_(3)]^(-)占主导,因而形成大量的CsPbBr_(3)纳米晶,随着反应的进行,体系中过量的Br^(-)会与纳米晶中的Pb相互作用,导致CsPbBr_(3)纳米晶部分转变为具有六边形形状的Cs_(4)PbBr_(6)纳米晶,同时[PbBr_(4)]^(2-)络合物的存在使得Cs_(4)PbBr_(6)纳米晶继续长大,最终形成以CsPbBr_(3)为发光中心的CsPbBr_(3)-Cs_(4)PbBr_(6)复合纳米晶.只有当TOABr用量为0.32 mmol时所得的CsPbBr_(3)-Cs_(4)PbBr_(6)复合纳米晶其光学性能和稳定性表现最佳.在此浓度下改变Cs/Pb摩尔比只影响CsPbBr_(3)纳米晶和Cs_(4)PbBr_(6)纳米晶在体系中的相对含量,当Cs_(4)PbBr_(6)纳米晶含量较高时其荧光强度和稳定性相对较差.该工作对低温可控合成高效稳定的铯铅卤钙钛矿纳米晶提供一定思路.All-inorganic cesium lead halide perovskites have shown great potential applications in optoelectronic field due to their fascinating optical properties.Although perovskite materials have achieved great success in various fields,their inherent ionic properties and high dynamic surface properties have led to their poor stability,hindering their applications.The preparation of CsPbBr_(3)-Cs_(4)PbBr_(6)nanocrystals has proven to be an effective strategy to enhance their photoluminescence properties and stability.Herein,we report an easy synthesis of CsPbBr_(3)-Cs_(4)PbBr_(6)nanocrystals with a diphase structure at room temperature by using Cs-OA,Pb-OA and TOABr as precursors in toluene.It is found that the phase transformation and the relative composition between CsPbBr_(3)and Cs_(4)PbBr_(6)are dependent on the concentration of TOABr and the ratio of Cs/Pb.The in-situ PL experiments reveal that the formation of~12 nm CsPbBr_(3)nanocubes experiences the fast nucleation,the focusing growth of size-distribution in early growth stage and Ostwald ripening growth in the later stage at a TOABr concentration of 0.16 mmol.With the increase of concentration of TOABr or molar ratio of Cs/Pb>1(Cs/Pb<1),[PbBr_(4)]^(2-)complex and[PbBr_(3)]^(-)complex can coexist and compete with each other in toluene,and the CsPbBr_(3)nucleations dominate in the early stage,then CsPbBr_(3)-Cs_(4)PbBr_(6)nanocomposites are gradually formed on CsPbBr_(3)nucleations as photoluminescence centers due to the continuous generation of[PbBr_(4)]^(2-)complex between TOABr and Pb^(2+).The relative composition of Cs_(4)PbBr_(6)in CsPbBr_(3)-Cs_(4)PbBr_(6)nanocomposites can be improved from 4%to 85%with the concentration of TOABr increasing or Cs/Pb<1.The optimized CsPbBr_(3)-Cs_(4)PbBr_(6)composite nanocrystals possess high PLQY and stability.Our work provides an understanding of the mechanism of phase transformation in cesium lead halide perovskite materials.

关 键 词：CsPbBr_(3)-Cs_(4)PbBr_(6)复合纳米晶 原位研究 相转变 形成动力学 

分 类 号：TB383.1[一般工业技术—材料科学与工程]