  The geometrical structure and photoexcitation properties of Zn27-nCdnO27C42
complexes are investigated by density functional theory (DFT) and
time-dependent DFT calculations at the PBE0/6-31G*/SDD level of theory. The
cohesive energy and frequency analysis indicate that the hybrid materials are
energetically stable. In presence of Cd substituting atoms, energy gap of the
ZnO nanodots surrounded by carbon moiety is shown to decrease, as compared to
Cd-free complex. In-depth excited state analysis including charge density
difference (CDD) mapping and absorption spectrum decomposition is performed to
reveal the nature of the dominant excited states and to comprehend the Cd-to-Zn
substitution effect on the photoexcitation properties of Zn27-nCdnO27C42. A
principal possibility to enhance intramolecular charge transfer through
incorporation of certain number of Cd atoms into the ZnO nanodots is shown.
Such Cd-induced modifications in optical properties of semi-spherical
Zn27-nCdnO27C42 complexes could potentially enable use of this hybrid material
in optoelectronic and photocatalytic applications.
