Spanopoulos Ioannis, Hadar Ido, Ke Weijun, Guo Peijun, Mozur Eve M, Morgan Emily, Wang Shuxin, Zheng Ding, Padgaonkar Suyog, Manjunatha Reddy G N, Weiss Emily A, Hersam Mark C, Seshadri Ram, Schaller Richard D, Kanatzidis Mercouri G
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States.
J Am Chem Soc. 2021 May 12;143(18):7069-7080. doi: 10.1021/jacs.1c01727. Epub 2021 Apr 27.
Hybrid halide perovskites consisting of corner-sharing metal halide octahedra and small cuboctahedral cages filled with counter cations have proven to be prominent candidates for many high-performance optoelectronic devices. The stability limits of their three-dimensional perovskite framework are defined by the size range of the cations present in the cages of the structure. In some cases, the stability of the perovskite-type structure can be extended even when the counterions violate the size and shape requirements, as is the case in the so-called "hollow" perovskites. In this work, we engineered a new family of 3D highly defective yet crystalline "hollow" bromide perovskites with general formula (FA)()(Pb)(Br) (FA = formamidinium (FA), = ethylenediammonium (), = 0-0.44). Pair distribution function analysis shed light on the local structural coherence, revealing a wide distribution of Pb-Pb distances in the crystal structure as a consequence of the Pb/Br-deficient nature and inclusion in the lattice. By manipulating the number of Pb/Br vacancies, we finely tune the optical properties of the pristine FAPbBr by blue shifting the band gap from 2.20 to 2.60 eV for the = 0.42 sample. A most unexpected outcome was that at > 0.33 incorporation, the material exhibits strong broad light emission (1% photoluminescence quantum yield (PLQY)) that is maintained after exposure to air for more than a year. This is the first example of strong broad light emission from a 3D hybrid halide perovskite, demonstrating that meticulous defect engineering is an excellent tool for customizing the optical properties of these semiconductors.
由角共享金属卤化物八面体和填充有抗衡阳离子的小立方八面体笼组成的混合卤化物钙钛矿已被证明是许多高性能光电器件的突出候选材料。其三维钙钛矿框架的稳定性极限由结构笼中存在的阳离子的尺寸范围定义。在某些情况下，即使抗衡离子违反尺寸和形状要求，钙钛矿型结构的稳定性也可以扩展，就像所谓的“空心”钙钛矿那样。在这项工作中，我们设计了一个新的3D高度缺陷但结晶的“空心”溴化物钙钛矿家族，其通式为(FA)()(Pb)(Br) （FA = 甲脒鎓(FA)， = 乙二铵()， = 0 - 0.44）。对分布函数分析揭示了局部结构相干性，由于Pb/Br缺陷性质和晶格中包含 ，晶体结构中Pb - Pb距离存在广泛分布。通过控制Pb/Br空位的数量，我们对原始FAPbBr的光学性质进行了微调，对于 = 0.42的样品，带隙从2.20蓝移到2.60 eV。一个最意想不到的结果是，当掺入量 > 0.33时，该材料表现出强烈的宽带发光（光致发光量子产率(PLQY)为1%），在暴露于空气中一年多后仍能保持。这是3D混合卤化物钙钛矿发出强烈宽带光的第一个例子，表明精心的缺陷工程是定制这些半导体光学性质的出色工具。
