Zinc Chalcogenide Based Colloidal Nanoplatelets

Two-dimensional colloidal nanoplatelets have become an attractive class of colloidal nanocrystals. With their thickness dependent excitonic properties, they exhibit exciting performance in optoelectronic devices. However, the most widely studied family of colloidal nanoplatelets are based on cadmium chalcogenides, which are considered as toxic materials and their optical properties cover very limited range of the electromagnetic spectrum. To overcome these limitations, we studied the synthesis of zinc chalcogenide based nanoplatelets with two different approaches: cation exchange and direct synthesis. For the cation exchange experiments, we firstly synthesized CdSe/ZnS core/shell NPLs and then performed cation exchange. With this approach, we can achieve core/shell nanoplatelets emitting in the blue spectral region (450 – 480 nm) by preserving their narrower emission linewidth (< 30 nm). In the second approach, we tried direct synthesis of zinc chalcogenide based nanoplatelets. We demonstrated that it is also possible to synthesize ZnSe nanoplatelets having zinc-blende crystal structure with direct synthesis approach. With our optimized synthesis conditions, we synthesized two different population of ZnSe nanoplatelets having absorption peaks at 347 and 369 nm.