Sequential Cation Exchange in InP Magic-Sized Clusters

Semiconductor nanomaterials with complex compositions have emerged as next-generation materials for applications in catalysis, energy storage, and sensing. Despite achieving high-quality doped II-VI and III-V semiconductor nanocrystals in specific cases, a general approach to compositional control is lacking. Leveraging the metastability of semiconductor magic-sized clusters (MSCs), we demonstrate a general approach to sequential cation exchange under mild conditions. The sequential exchange begins with In37P20(O2CC13H27)51 MSCs and proceeds through a copper-doped intermediate to achieve Mn, Co, Fe, and Mo-doped clusters at ambient temperature. The resulting products are spectroscopically and structurally characterized to track changes in absorbance, composition, and size. Moreover, we use these doped clusters as seeds for the growth of doped InP nanocrystals, and in doing so, we find that the cluster dopant can be preserved throughout the growth process, resulting in different degrees of incorporation depending on the dopant identity. Finally, the addition of tributylphosphine and mild heating were employed as post-synthetic strategies to remove Cu impurities in the final doped nanocrystals. This mild approach for transition metal doping of MSCs through a sequential cation exchange reaction offers a new and versatile route toward doped and multicomponent nanocrystals.