Broadband Sensitization of Lanthanide Emission with Indium Phosphide Quantum Dots for Visible to Near-Infrared Downshifting

Semiconductor quantum dot (QD)-sensitized lanthanide ions hold great promise in producing a broadly absorbing and sharply emitting luminophore, but their synthesis has proven to be difficult. We report the first synthesis of core/shell/shell InP/Ln _xY_{1- x}F₃/ShF₃ (Ln = Yb, Nd; Sh = Lu, Y) nanocrystals that exhibit a broad visible absorption coupled to a sharp near-infrared emission. Additionally, this is the first report of Nd being coupled to a QD absorber. We characterize the system with a variety of electron microscopy and X-ray techniques that prove this unique structure. Optical measurements confirm the correlation of the Ln³⁺ emission to the QD absorption, while the presence of a trap-state emission gives a clue as to the mechanism of energy transfer between the dot and the lanthanide.