Two types of CdTeSe magic-size clusters from one ZnTeSe sample via cation exchange at room temperature

Little is known about the room-temperature formation of colloidal semiconductor magic-size clusters (MSCs) of II-VI ternary CdE₁E₂ from ZnE₁E₂. Here, we report the first synthesis of CdTeSe MSCs from ZnTeSe MSC-340 (displaying a sharp optical absorption peaking at 340 nm) at room temperature. When ZnTeSe MSC-340 and Cd(OAc)₂/OLA (made from cadmium acetate and oleylamine) were mixed, the former disappeared, while CdTeSe MSC-422 and/or MSC-399 developed. Based on our experimental data, we propose that the conversion proceeds via the interaction of Cd(OAc)₂/OLA and the precursor compound of ZnTeSe MSC-340, PC-340. As such, ZnTeSe MSC-340 first isomerized to PC-340; via cation exchange PC-340 transformed to CdTeSe PCs. In turn, the resultant CdTeSe PC isomerized to CdTeSe MSCs, the process of which was rate-determining. Furthermore, we show that the transformation between CdTeSe MSC-422 and MSC-399 was reversible, providing strong evidence that they are a pair of isomers. Our study introduces a room-temperature avenue towards Cd-based MSCs from Zn-based ones, which follows anionic framework conservation and anionic number conservation.