Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova , Via Dodecaneso 31, 16146 Genova, Italy.
J Am Chem Soc. 2018 Feb 21;140(7):2656-2664. doi: 10.1021/jacs.7b13477. Epub 2018 Feb 12.
We propose here a new colloidal approach for the synthesis of both all-inorganic and hybrid organic-inorganic lead halide perovskite nanocrystals (NCs). The main limitation of the protocols that are currently in use, such as the hot injection and the ligand-assisted reprecipitation routes, is that they employ PbX (X = Cl, Br, or I) salts as both lead and halide precursors. This imposes restrictions on being able to precisely tune the amount of reaction species and, consequently, on being able to regulate the composition of the final NCs. In order to overcome this issue, we show here that benzoyl halides can be efficiently used as halide sources to be injected in a solution of metal cations (mainly in the form of metal carboxylates) for the synthesis of APbX NCs (in which A = Cs, CHNH, or CH(NH)). In this way, it is possible to independently tune the amount of both cations and halide precursors in the synthesis. The APbX NCs that were prepared with our protocol show excellent optical properties, such as high photoluminescence quantum yields, low amplified spontaneous emission thresholds, and enhanced stability in air. It is noteworthy that CsPbI NCs, which crystallize in the cubic α phase, are stable in air for weeks without any postsynthesis treatment. The improved properties of our CsPbX perovskite NCs can be ascribed to the formation of lead halide terminated surfaces, in which Cs cations are replaced by alkylammonium ions.
我们在这里提出了一种新的胶体方法，用于合成全无机和有机-无机混合卤化铅钙钛矿纳米晶体（NCs）。目前使用的方法，如热注入和配体辅助再沉淀路线的主要限制是，它们使用 PbX（X = Cl、Br 或 I）盐作为铅和卤化物前体。这限制了能够精确调整反应物种的数量，从而限制了能够调节最终 NCs 组成的能力。为了克服这个问题，我们在这里表明，苯甲酰卤可以有效地用作卤化物源，注入金属阳离子（主要以金属羧酸盐的形式）的溶液中，用于合成 APbX NCs（其中 A = Cs、CHNH 或 CH(NH)）。通过这种方式，可以独立地调节合成中阳离子和卤化物前体的数量。我们的方案制备的 APbX NCs 具有出色的光学性能，例如高光致发光量子产率、低放大自发发射阈值和在空气中的增强稳定性。值得注意的是，在没有任何后合成处理的情况下，结晶为立方α相的 CsPbI NCs 在空气中稳定数周。我们的 CsPbX 钙钛矿 NCs 的改进性能可以归因于形成了终止于卤化铅的表面，其中 Cs 阳离子被烷基铵离子取代。
