Li Yanxiu, Huang He, Xiong Yuan, Richter Alexander F, Kershaw Stephen V, Feldmann Jochen, Rogach Andrey L
Department of Materials Science and Engineering, and Centre for Functional Photonics (CFP) , City University of Hong Kong , 83 Tat Chee Avenue , Kowloon , Hong Kong S.A.R.
Chair for Photonics and Optoelectronics, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany.
ACS Nano. 2019 Jul 23;13(7):8237-8245. doi: 10.1021/acsnano.9b03508. Epub 2019 Jul 11.
Semiconductor nanorods (NRs) offer the useful property of linearly polarized light emission. While this would be an attractive functionality for strongly emitting perovskite nanoparticles, to date, there has been limited success in demonstrating a direct chemical synthesis of cesium lead halide perovskite NRs. In this work, we realized the direct synthesis of CsPbBr NRs with an average width of around 5 nm and average lengths of 10.8 and 23.2 nm, respectively, in two samples, which show a high photoluminescence quantum yield of 60-76% and reasonably high emission anisotropy of about 0.2 for longer rods. Both CsPbCl and CsPbI NRs with similar dimensions have then been derived from the CsPbBr NRs by anion-exchange reactions. Remarkably, the synthesis of the NRs has been achieved in polar alcohols, a class of solvents not usually found to be beneficial in classical perovskite nanoparticle synthesis. This work not only offers the possibility to control the shape of chemically synthesized perovskite nanocrystals but also constitutes the hitherto less common strategy of synthesizing perovskite nanoparticles in polar rather than nonpolar or only weakly polar solvents.
半导体纳米棒（NRs）具有线性偏振光发射这一有用特性。虽然对于强发光的钙钛矿纳米颗粒而言，这将是一种有吸引力的功能，但迄今为止，在证明直接化学合成卤化铯铅钙钛矿NRs方面取得的成功有限。在这项工作中，我们在两个样品中实现了CsPbBr NRs的直接合成，其平均宽度约为5 nm，平均长度分别为10.8 nm和23.2 nm，这些样品显示出60 - 76%的高光致发光量子产率，对于较长的纳米棒，发射各向异性约为0.2，相当高。然后通过阴离子交换反应从CsPbBr NRs衍生出尺寸相似的CsPbCl和CsPbI NRs。值得注意的是，NRs的合成是在极性醇类中实现的，这类溶剂在传统的钙钛矿纳米颗粒合成中通常不被认为是有益的。这项工作不仅提供了控制化学合成钙钛矿纳米晶体形状的可能性，而且构成了迄今为止不太常见的在极性而非非极性或仅弱极性溶剂中合成钙钛矿纳米颗粒的策略。
