All-inorganic, CsPbX3 (X=Cl, Br, I) quantum dot nanocrystals have been shown to have great promise for optical and optoelectronic applications due to excellent stability, high fluorescent quantum yields, and optical tunability via a facile halide exchange reaction. This presentation will discuss our recent progress obtaining refined synthetic control over either cation exchange or, alternatively, metal deposition of Au with CsPbBr3 nanoparticles. The oleylamine ligand shell commonly used to stabilize all-inorganic perovskite nanocrystals may be used to reduce gold salts, allowing for Au to either exchange with Pb2+ in the perovskite crystal lattice or deposit as Au metal on the surface of the nanocrystals. Our central insight is that the reaction kinetics for exchange or deposition are driven by the excess metal cation in solution. When gold salt alone is added, cation exchange occurs, but if an excess of Pb2+ is added, Au metal only deposits on the perovskite surface with domain size determined by the gold solution concentration. While the cation exchange reaction represents a new manner of post-synthetic tunability that may aid in the search for lead free all-inorganic perovskite, most remarkable is the high fluorescence quantum yield maintained in Au-CsPbBr3 heterostructures with efficiencies up to 75%. This surprising result could provide new insights into the optoelectronic properties of the all-inorganic perovskite nanocrystals, as well as the interactions between metal and semiconductors on the nanoscale.

Au exchange or Au deposition: Control of morphology in Au-CsPbBr3 heterostructure nanoparticles

254th National Meeting (2017)

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