Synthesis of Uniform Disk-Shaped Copper Telluride Nanocrystals and Cation Exchange to Cadmium Telluride Quantum Disks with Stable Red Emission
Open Access
- 6 August 2013
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 135 (33), 12270-12278
- https://doi.org/10.1021/ja404694k
Abstract
We present the synthesis of novel disk-shaped hexagonal Cu2Te nanocrystals with a well-defined stoichiometric composition and tunable diameter and thickness. Subsequent cation exchange of Cu to Cd at high temperature (180 degrees C) results in highly fluorescent CdTe nanocrystals, with less than 1 mol 96 of residual Cu remaining in the lattice. The procedure preserves the overall disk shape, but is accompanied by a substantial reconstruction of the anion sublattice, resulting in a reorientation of the c-axis from the surface normal in Cu2Te into the disk plane in CdTe nanodisks. The synthesized CdTe nanodisks show a continuously tunable photoluminescence (PL) peak position, scaling with the thickness of the disks. The PL lifetime further confirms that the CdTe PL arises from band-edge exciton recombination; that is, no Cu-related emission is observed. On average, the recombination rate is about 25-45% faster with respect to their spherical quantum dots counterparts, opening up the possibility to enhance the emission rate at a given wavelength by controlling the nanocrystal shape. Finally, with a PL quantum efficiency of up to 36% and an enhanced PL stability under ambient conditions due to a monolayer of CdS formed on the nanocrystal surface during cation exchange, these flat quantum disks form an interesting enrichment to the current family of highly fluorescent, shape-controlled nanocrystals.Keywords
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