Seeded Growth of Nanoscale Semiconductor Tetrapods: Generality and the Role of Cation Exchange

Abstract

Nanoscale tetrapods were synthesized with independently tunable core and arm sizes and aspect ratios from a spectrum of quantum dot seeds, including ZnTe, CuInS2, InP, InP/ZnS, and Cd3P2. The range of II–VI, I–III–VI, III–V, and II–V seeds included both cubic and tetragonal lattices, demonstrating the versatility of CdS arm growth upon surfaces with accessible (111) planes, including those with distorted those with distorted structures. Except for the Cd3P2 seeds, where the effect is inconsequential, cation exchange in the core was observed to occur concurrently with arm growth to give alloyed cores in the final tetrapods. This result supports recent work characterizing the composition of core/shell quantum dots composed of distinct cations and presents a challenge to achieving clean interfaces in nanoscale semiconductor heterostructures grown by using traditional solvothermal methods. Conversely, the robust Cd3P2/CdS tetrapod architecture represents a rare example of near-infrared (NIR) emission in a multipod heterostructure. NIR-emissive tetrapod heterostructures were successfully obtained from Cd3P2 cores in combination with both high and low aspect ratio CdS arms.