Abstract
Concentration-dependent optical properties of lead sulfide (PbS) quantum dots (QDs) embedded into a porous matrix are investigated. A red shift of luminescence peak position depends on QD concentration and evidences for F¨orster resonant energy transfer (FRET) inside the quasi-monodispersed assemblies. PL decay curves show significant influence of FRET process on QD optical properties. PL lifetime size-dependencies are found to be dependent on the QD concentration. The growing impact of FRET process with increasing QD concentration leads to transformation of anomalous size-dependence of PL lifetimes to the inverse. FRET efficiency gradually increases with QD concentration and saturates at 35% that corresponds to the formation of an ordered QD superstructure. Formation of PbS QD superstructure is confirmed by X-ray analysis, while calculated interdot distance in the superstructure coincides with the one obtained by FRET technique.
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