Size controlled ultranarrow PbS nanorods: spectroscopy and robust stability

Abstract

We describe a simple route for designing ultranarrow PbS rods of 1.7 nm in diameter in a single step under bench-top reaction conditions. The rods are size controlled into 2.5 nm diameter by tuning the reaction temperature. Both the nanorods exhibit molecule-like discrete narrow optical behavior with high fluorescence quantum yield. The confinement owing to the change in diameter is reflected in absorption and photoluminescence spectroscopy. The strength of the exciton–phonon coupling has been evaluated from the Fröhlich coupling and Huang–Rhys parameter in the adiabatic approximation using Raman spectroscopy, which reveals a different degree of confinement in size controlled rods. The thermogravimetric analysis reveals robustness of these nanorods. Such ultranarrow size controlled nanorods are of fundamental scientific interest and in principle can find potential applications in nanorod based devices. The nanorods with strong discrete fluorescence and robust stability could be useful in biological labeling, fluorescence resonance energy transfer and optoelectronic applications.