The room-temperature structural and optical transformation of cadmium chalcogenide quantum dots triggered by reactive cations

Colloidal cadmium chalcogenide quantum dots can exhibit a drastic change in structure and conformation by addition of a metal cation with a positive redox potential. CdTe and CdSe nanoparticles mixed with a mercury cation were transformed into alloyed anisotropic structures with red-shifted optical properties. Additionally the same cation addition to CdSe nanorods caused oriented attachment and resulted in a series of end-to-end superstructures. In the case of gold cation addition, CdTe nanoparticles yielded gold based anisotropic structures which had poor solubility in the original solvent. CdTe nanoparticles mixed with lead, zinc and cadmium cations, however, kept their original optical properties after the same reaction procedure. Combining these observations with the previously reported chemical transformation from cadmium chalcogenides to silver/copper chalcogenides, we highlight the role of the redox potentials when describing the change in structural/optical property in colloidal cadmium chalcogenide nanocrystals.