Structural Diversity in Cesium Bismuth Halide Nanocrystals
Structural Diversity in Cesium Bismuth Halide Nanocrystals
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DOI：
10.1021/acs.chemmater.9b00640
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发表时间：
2019-07-09
影响因子：
8.6
通讯作者：
Gamelin, Daniel R.
中科院分区：
文献类型：
--
作者：
Creutz, Sidney E.;Liu, Hongbin;Gamelin, Daniel R.
卤化铯铋（Cs-Bi-X）作为用于发光和光致发光应用的卤化铅钙钛矿的可能的毒性较低的替代物最近已经受到相当大的关注，但是合成可获得的Cs-Bi-X组合物的全部范围尚未被彻底探索，并且在文献中出现了一些不一致的结果。在这里，我们使用了热注入合成和合成后阴离子交换的组合来制备具有许多结构和组成的Cs-Bi-X纳米晶体，包括一些以前没有被表征的。报道了Cs3 BiX 6（X = Cl，Br，I）纳米晶和Cs3 Bi 2X 9（X = Cl，Br，I）纳米片的结构和光学性质，并通过使用三甲基硅基卤化物的阴离子交换证明了这些结构在不同卤化物组成之间的相互转化。值得注意的是，我们发现阴离子交换可以用于获得不容易通过直接合成制备的结构多晶型物。特别是，一种新的结构修改Cs3 Bi 2 I9已被访问;而热注入给出了先前报道的“零维”非钙钛矿结构，阴离子交换提供了访问一个“二维”分层，有序空位钙钛矿相与红移的吸收光谱和明显不同的光致发光。这些材料的光谱和计算表征提供了对结构/性质关系的洞察，包括层状Cs3 Bi 2 I9材料的性质，这可能有利于光电应用。
Cesium bismuth halides (Cs-Bi-X) have recently been the subject of considerable attention as possible less-toxic alternatives to lead halide perovskites for luminescence and photovoltaics applications, but the full range of synthetically accessible Cs-Bi-X compositions has not been thoroughly explored, and some inconsistent results have appeared in the literature. Here, we have used a combination of hot-injection synthesis and post-synthetic anion exchange to prepare Cs-Bi-X nanocrystals with many structures and compositions, including several that have not previously been characterized. The structural and optical properties of Cs3BiX6 (X = Cl, Br, I) nanocrystals and Cs3Bi2X9 (X = Cl, Br, I) nanoplatelets are reported, and interconversion of these structures between different halide compositions is demonstrated through anion exchange using trimethylsilyl halides. Notably, we find that anion exchange can be used to access structural polymorphs not readily prepared through direct synthesis. In particular, a new structural modification of Cs3Bi2I9 has been accessed; whereas hot injection gives the previously reported "zero-dimensional" nonperovskite structure, anion exchange provides access to a "two-dimensional" layered, ordered-vacancy perovskite phase with a red-shifted absorption spectrum and distinctly different photoluminescence. Spectroscopic and computational characterization of these materials provides insight into structure/property relationships, including properties of the layered Cs3Bi2I9 material, that may be advantageous for optoelectronic applications.