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 and mechanical 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 preparation method of long-chain cadmium(II) carboxylates and their effect on NPL synthesis. In the case of cadmium(II) oleate, we show that two structures (amorphous and lamellar) coexist, and their relative concentration depends on the synthesis method used to prepare the precursor. In contrast, cadmium(II) myristate always crystallizes in a lamellar structure. During the NPL synthesis, the dissolution kinetics, which occurs at high temperatures, impacts the amount of cadmium available to grow NPL seeds and is related to its supramolecular organization. Slowly dissolving precursors yield thicker NPL.