Li Zhanzhao, Goldoni Luca, Wu Ye, Imran Muhammad, Ivanov Yurii P, Divitini Giorgio, Zito Juliette, Panneerselvam Iyyappa Rajan, Baranov Dmitry, Infante Ivan, De Trizio Luca, Manna Liberato
Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163, Italy.
Chemistry Facility, Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163, Italy.
J Am Chem Soc. 2024 Jul 31;146(30):20636-20648. doi: 10.1021/jacs.4c03084. Epub 2024 Jul 17.
Current syntheses of CsPbBr halide perovskite nanocrystals (NCs) rely on overstoichiometric amounts of Pb precursors, resulting in unreacted lead ions at the end of the process. In our synthesis scheme of CsPbBr NCs, we replaced excess Pb with different exogenous metal cations (M) and investigated their effect on the synthesis products. These cations can be divided into two groups: group 1 delivers monodisperse CsPbBr cubes capped with oleate species (as for the case when Pb is used in excess) and with a photoluminescence quantum yield (PLQY) as high as 90% with some cations (for example with M = In); group 2 yields irregularly shaped CsPbBr NCs with broad size distributions. In both cases, the addition of a tertiary ammonium cation (didodecylmethylammonium, DDMA) during the synthesis, after the nucleation of the NCs, reshapes the NCs to monodisperse truncated cubes. Such NCs feature a mixed oleate/DDMA surface termination with PLQY values of up to 97%. For group 1 cations this happens only if the ammonium cation is directly added as a salt (DDMA-Br), while for group 2 cations this happens even if the corresponding tertiary amine (DDMA) is added, instead of DDMA-Br. This is attributed to the fact that only group 2 cations can facilitate the protonation of DDMA by the excess oleic acid present in the reaction environment. In all cases studied, the incorporation of M cations is marginal, and the reshaping of the NCs is only transient: if the reactions are run for a long time, the truncated cubes evolve to cubes.
目前合成CsPbBr卤化物钙钛矿纳米晶体（NCs）依赖于化学计量过量的Pb前驱体，导致在过程结束时存在未反应的铅离子。在我们合成CsPbBr NCs的方案中，我们用不同的外源金属阳离子（M）取代了过量的Pb，并研究了它们对合成产物的影响。这些阳离子可分为两组：第1组产生用油酸根物种封端的单分散CsPbBr立方体（与使用过量Pb的情况相同），并且一些阳离子（例如M = In）的光致发光量子产率（PLQY）高达90%；第2组产生尺寸分布较宽的形状不规则的CsPbBr NCs。在这两种情况下，在NCs成核后合成过程中添加叔铵阳离子（十二烷基二甲基铵，DDMA），会将NCs重塑为单分散的截角立方体。此类NCs具有混合的油酸根/DDMA表面终止结构，PLQY值高达97%。对于第1组阳离子，只有当铵阳离子作为盐（DDMA-Br）直接添加时才会发生这种情况，而对于第2组阳离子，即使添加相应的叔胺（DDMA）而不是DDMA-Br也会发生这种情况。这归因于只有第2组阳离子能够促进反应环境中存在的过量油酸使DDMA质子化。在所研究的所有情况下，M阳离子的掺入量很少，并且NCs的重塑只是暂时的：如果反应进行很长时间，截角立方体会演变成立方体。
