Chen Shulin, Wang Jiayi, Thomas Simil, Mir Wasim J, Shao Bingyao, Lu Jianxun, Wang Qingxiao, Gao Peng, Mohammed Omar F, Han Yu, Bakr Osman M
KAUST Catalysis Center (KCC), Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Changsha Semiconductor Technology and Application Innovation Research Institute, College of Semiconductors (College of Integrated Circuits), Hunan University, Changsha 410082, China.
Nano Lett. 2023 Jul 12;23(13):6002-6009. doi: 10.1021/acs.nanolett.3c01189. Epub 2023 Jun 21.
Inorganic halide perovskite nanocrystals (NCs) are being widely explored as next-generation optoelectronic materials. Critical to understanding the optoelectronic properties and stability behavior of perovskite NCs is the material's surface structure, where the local atomic configuration deviates from that of the bulk. Through low-dose aberration-corrected scanning transmission electron microscopy and quantitative imaging analysis techniques, we directly observed the atomic structure at the surface of the CsPbBr NCs. CsPbBr NCs are terminated by a Cs-Br plane, and the surface Cs-Cs bond length decreases significantly (∼5.6%) relative to the bulk, imposing compressive strain and inducing polarization, which we also observed in CsPbI NCs. Density functional theory calculations suggest such a reconstructed surface contributes to the separation of holes and electrons. These findings enhance our fundamental understanding of the atomic-scale structure, strain, and polarity at the surface of inorganic halide perovskites and provide valuable insights into designing stable and efficient optoelectronic devices.
无机卤化物钙钛矿纳米晶体（NCs）作为下一代光电器件材料正受到广泛探索。理解钙钛矿NCs的光电特性和稳定性行为的关键在于材料的表面结构，其中局部原子构型与体相不同。通过低剂量像差校正扫描透射电子显微镜和定量成像分析技术，我们直接观察到了CsPbBr NCs表面的原子结构。CsPbBr NCs由一个Cs-Br平面终止，表面Cs-Cs键长相对于体相显著缩短（约5.6%），产生压缩应变并诱导极化，我们在CsPbI NCs中也观察到了这一现象。密度泛函理论计算表明，这种重构表面有助于空穴和电子的分离。这些发现增进了我们对无机卤化物钙钛矿表面原子尺度结构、应变和极性的基本理解，并为设计稳定高效的光电器件提供了有价值的见解。
