Malgras Victor, Tominaka Satoshi, Ryan James W, Henzie Joel, Takei Toshiaki, Ohara Koji, Yamauchi Yusuke
World Premier International (WPI) Research Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS) , 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
J Am Chem Soc. 2016 Oct 26;138(42):13874-13881. doi: 10.1021/jacs.6b05608. Epub 2016 Oct 13.
Hybrid organic-inorganic metal halide perovskites have fascinating electronic properties and have already been implemented in various devices. Although the behavior of bulk metal halide perovskites has been widely studied, the properties of perovskite nanocrystals are less well-understood because synthesizing them is still very challenging, in part because of stability. Here we demonstrate a simple and versatile method to grow monodisperse CHNHPbBrI perovskite nanocrystals inside mesoporous silica templates. The size of the nanocrystal is governed by the pore size of the templates (3.3, 3.7, 4.2, 6.2, and 7.1 nm). In-depth structural analysis shows that the nanocrystals maintain the perovskite crystal structure, but it is slightly distorted. Quantum confinement was observed by tuning the size of the particles via the template. This approach provides an additional route to tune the optical bandgap of the nanocrystal. The level of quantum confinement was modeled taking into account the dimensions of the rod-shaped nanocrystals and their close packing inside the channels of the template. Photoluminescence measurements on CHNHPbBr clearly show a shift from green to blue as the pore size is decreased. Synthesizing perovskite nanostructures in templates improves their stability and enables tunable electronic properties via quantum confinement. These structures may be useful as reference materials for comparison with other perovskites, or as functional materials in all solid-state light-emitting diodes.
有机-无机杂化金属卤化物钙钛矿具有迷人的电子特性，已被应用于各种器件中。尽管块状金属卤化物钙钛矿的行为已得到广泛研究，但钙钛矿纳米晶体的性质却鲜为人知，因为合成它们仍然极具挑战性，部分原因在于其稳定性。在此，我们展示了一种简单且通用的方法，可在介孔二氧化硅模板内部生长单分散的CHNHPbBrI钙钛矿纳米晶体。纳米晶体的尺寸由模板的孔径（3.3、3.7、4.2、6.2和7.1纳米）决定。深入的结构分析表明，纳米晶体保持了钙钛矿晶体结构，但略有扭曲。通过模板调节颗粒尺寸观察到了量子限域效应。这种方法为调节纳米晶体的光学带隙提供了一条额外途径。考虑到棒状纳米晶体的尺寸及其在模板通道内的紧密堆积情况，对量子限域水平进行了建模。对CHNHPbBr的光致发光测量清楚地表明，随着孔径减小，发光颜色从绿色变为蓝色。在模板中合成钙钛矿纳米结构可提高其稳定性，并通过量子限域实现可调谐的电子特性。这些结构可用作与其他钙钛矿进行比较的参考材料，或用作全固态发光二极管中的功能材料。
