Ab Initio Molecular Dynamics of CdSe Quantum-Dot-Doped Glasses

We
have probed the local atomic structure of the interface between
a CdSe quantum dot (QD) and a sodium silicate glass matrix. Using
ab initio molecular dynamics simulations, we determined the structural
properties and bond lengths, in excellent agreement with previous
experimental observations. On the basis of an analysis of radial distribution
functions, coordination environment, and ring structures, we demonstrate
that an important structural reconstruction occurs at the interface
between the CdSe QD and the glass matrix. The incorporation of the
CdSe QD disrupts the Na–O bonds, while stronger SiO4 tetrahedra are reformed. The existence of the glass matrix breaks
the stable 4-membered (4MR) and 6-membered (6MR) Cd–Se rings,
and we observe a disassociated Cd atom migrated in the glass matrix.
Besides, the formation of Se–Na and Cd–O linkages is
observed at the CdSe QD/glass interface. These results significantly
extend our understanding of the interfacial structure of CdSe
QD-doped glasses and provide physical and chemical insight into the
possible defect structure origin of CdSe QD, of interest to the fabrication
of the highly luminescent CdSe QD-doped glasses.