Seeded Growth of Mesoscale Quantum-Confined Semiconductor Nanoplatelets

Colloidally grown (II-VI) semiconductor nanoplatelets display significantly smaller lateral dimensions than their mechanically exfoliated 2D van der Waal (vdW) semiconductor counterparts. Here, we show that a seeded growth procedure allows us to significantly extend the lateral area of atomically precise nanoplatelets to the mesoscale (>1 μm^2). Using CdTe nanoplatelets as a model system, we optimize reaction parameters to expand a variety of nanoplatelets with different thickness and compositions. In situ spectroscopy results demonstrate that large NPLs grow through a mechanism of lateral ripening of seeds. Correlative optical spectroscopy and electron microscopy measurements show that the photoluminescence displays resolvable spatial inhomogeneities, similar to 2D semiconductors. Overall, these mesoscale nanoplatelets can be analogized to vdW semiconductors, with the added advantages of scalable colloidal synthesis, thickness tunability and solution processability.