Optical properties of IV–VI quantum dots embedded in glass: Size-effects

Measurements of the photoluminescence (PL), micro-PL, spatially-resolved PL, optical absorption and atomic force microscopy (AFM) of PbS and PbSe quantum dots (QDs) embedded in oxide glass matrix, were carried out. It was found that the energy gaps of the QDs showed pronounced anomalous temperature dependences. Their temperature coefficients depended strongly upon the size and shape of the QDs, and surface and/or confined phonon modes. In addition, the energy-dependent transfer rate of excitons from smaller to larger dots via electronic coupling was observed. It was predicted that further improvements in size selectivity, luminescence quantum yield, and well-controlled growth would enable highly efficient inter-dot energy transfer.