We study size dependence of kinetic and spectral properties of near-infrared luminescence from PbS quantum
dots in colloidal solution. Luminescence lifetimes are found to lie between 250 ns for the largest quantum
dots and 2:5 μs for the smallest ones, while the Stoke's shift is found to increase from 4-5 to 300 meV. These
results are explained by the presence of the long-living in-gap state, with the size-dependent energy. Analytical
modeling shows that the relaxation from this state is dominant in small quantum dots and negligible in large ones.
Biexponential luminescence decay with the size-dependent recombination rates is predicted for quantum dots
of all sizes.
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Alexander P. Litvin ; Peter S. Parfenov ; Elena V. Ushakova ; Anatoly V. Fedorov ; Mikhail V. Artemyev, et al.
Size-dependent room-temperature luminescence decay from PbS quantum dots
", Proc. SPIE 8564, Nanophotonics and Micro/Nano Optics, 85641Z (November 20, 2012); doi:10.1117/12.2001073; http://dx.doi.org/10.1117/12.2001073