  Electronic coupling and hence hybridization of atoms serve as the basis for
the rich properties of the endless library of naturally occurring molecules.
Colloidal quantum dots (CQDs) manifesting quantum strong confinement, possess
atomic like characteristics with s and p electronic levels, which popularized
the notion of CQDs as artificial atoms. Continuing this analogy, when two atoms
are close enough to form a molecule so that their orbitals start overlapping,
the orbitals' energies start to split into bonding and anti-bonding states made
out of hybridized orbitals. The same concept is also applicable for two fused
core-shell nanocrystals in close proximity. Their band-edge states, which
dictate the emitted photon energy, start to hybridize changing their electronic
and optical properties. Thus, an exciting direction of artificial molecules
emerges leading to a multitude of possibilities for creating a library of new
hybrid nanostructures with novel optoelectronic properties with relevance
towards diverse applications including quantum technologies. In a model fused
core-shell homodimer molecule, the hybridization energy is strongly correlated
with the extent of structural continuity, the delocalization of the exciton
wavefunction, and the barrier thickness as calculated numerically. The
hybridization impacts the emitted photon statistics manifesting a faster
radiative decay rate, photon bunching effect, and modified Auger recombination
pathway compared to the monomer artificial atoms. Future perspectives for the
nanocrystals chemistry paradigm are highlighted.
