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Chalcogenide-Bound Erbium Complexes: Paradigm Molecules for Infrared Fluorescence Emission

The near-infrared luminescence properties of the nanoscale erbium ceramic cluster (THF)14Er10S6Se12I6 (Er10, where THF = tetrahydrofuran) and the molecular erbium thiolate (DME)2Er(SC6F5)3 (Er1, where DME = 1,2-dimethoxyethane) were studied by optical absorption, photoluminescence, and vibrational spectroscopy. The calculated radiative decay time of 4 ms for the 4I13/2 → 4I15/2 transition is comparable to the reported values for previously reported organic complexes. The recorded emission spectrum of the 4I13/2 → 4I15/2 transition was centered at 1544 nm with a bandwidth of 61 and 104 nm for Er10 and Er1, respectively, with stimulated emission cross sections of 1.3 × 10-20 cm2 (Er10) and 0.8 × 10-20 cm2 (Er1) that are comparable to those of solid-state inorganic systems. Lifetime measurements of the 1544 nm decay showed a fluorescence decay time of the order of 3 ms for Er10 that, together with the radiative decay time, yielded a quantum efficiency above 78%, which is considered to be the highest reported...