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Core-Shell Heterostructures for Photovoltaic Energy Conversion
Igor Vasiliev, Department of Physics, New Mexico State University, Las Cruces, NM 88003
Our research focuses on theoretical prediction of the structural, electronic, and optical properties of coreshell semiconductor nanoparticles. The goal of this project is to expand the knowledge of chemistry and
physics of semiconductor heterostructures and accelerate the development of composite materials for
efficient conversion of solar energy.
Structural optimization of core-shell
semiconductor nanoparticles: Two
types of core-shell nanoparticles were
considered in our study: traditional,
in which a core of a narrow gap semiconductor is covered with a shell of a
wide gap material, and inverted, in
which a wide-gap core is enclosed in
a narrow-gap shell. The structures of
nanoparticles were optimized using
ab initio computational methods based
on density functional theory. The
surfaces of nanoparticles were passivated with partially charged hydrogen atoms. This approach removed
the electronic states associated with
the surface atoms from the gap. We
found that CdSe/ZnSe and ZnSe/CdSe
nanoparticles based on the sphalerite
form of CdSe were lower in energy
than those based on the wurtzite form
of CdSe.
Inverted (a) and traditional (b) core-shell semiconductor nanoparticles
Optimized structures of ZnSe/CdSe and CdSe/ZnSe nanoparticles