Cadmium carboxylate preparation method impacts the synthesis of CdSe Nanoplatelets through differences in dissolution kinetics

Colloidal CdSe nanoplatelets (NPL) are promising materials for various applications due to their unique optical properties arising from their atomically controlled thickness. However, the lack of understanding of their formation mechanism can result in low yields, multiple side products that are hard to separate, and unknown ligand composition at their surface. All these factors hinder the development and exploitation of such nanocrystals in devices. Herein, we focused on assessing the effect of long-chain cadmium(II) carboxylates (oleate and myristate) preparation methods on NPL synthesis. While cadmium(II) myristate always crystallizes in a lamellar structure irrespective of its preparation pathway, we show that cadmium(II) oleate displays two structures, one amorphous and one lamellar, that coexist in different relative concentrations depending on the synthesis method used to prepare the precursor. These differences impact the NPL synthesis through the precursor dissolution rate, which varies according to its supramolecular structure. The lamellar structure dissolves faster and yields thinner NPL than the amorphous one.