Exogenous Metal Cations in the Synthesis of CsPbBr3 Nanocrystals and Their Interplay with Tertiary Amines

• Published in: Journal of the American Chemical Society Vol. 146; no. 30; pp. 20636 - 20648
• Main Authors: 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
• Format: Journal Article
• Language: English
• Published: American Chemical Society 31-07-2024
• Subjects: Chemical Sciences; Kemi; Materialkemi; Materials Chemistry; Natural Sciences; Naturvetenskap
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c03084

Current syntheses of CsPbBr3 halide perovskite nanocrystals (NCs) rely on overstoichiometric amounts of Pb2+ precursors, resulting in unreacted lead ions at the end of the process. In our synthesis scheme of CsPbBr3 NCs, we replaced excess Pb2+ 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 CsPbBr3 cubes capped with oleate species (as for the case when Pb2+ is used in excess) and with a photoluminescence quantum yield (PLQY) as high as 90% with some cations (for example with M = In3+); group 2 yields irregularly shaped CsPbBr3 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.