Structural and optical properties of ZnSe quantum dots in glass nanocomposites

Zinc selenide (ZnSe) quantum dots (QDs) were synthesized in a dielectric (borosilicate glass) matrix for the first time by melt-quenching process followed by thermal treatment. Sizes of the quantum dots were varied by post thermal treatment. UV-Vis optical absorption spectroscopy, transmission electron microscopy (TEM) and Raman spectroscopy were deployed to investigate the ZnSe QDs. TEM analysis reveals QD sizes of the order of 2-4 nm and relatively larger nanocrystals having sizes of the order of 15-26 nm. The sizes of the QDs have also been verified with the help of effective mass approximation model and optical absorption spectroscopy. The quantum confinement effect has been observed for both variation of heat treatment temperature and time. The Raman spectra of the nanocomposites reveal blue-shifted Raman peaks of ZnSe at 295 and 315 cm−1 due to phonon confinement effect. The decrease in Raman intensity with heat treatment indicates increase in size of the QDs. Red luminescence from the ZnSe-glass nanocomposites peaking at 708 nm due to the size related as well as traps related states makes their applications towards luminescent solar concentrators (LSCs).