1 research outputs found
First Principle Study of Capping Energies and Electronic States in Stoichiometric and Nonstoichiometric PbSe Nanoclusters
A large
variety of PbSe nanoclusters have been modeled at the DFT
level, to study their structure, their affinity for different ligands
and their electronic properties, also depending on surface passivation.
The clusters are extracted from the bulk rock salt structure with
cubic, prism, truncated cubic, cuboctahedral and octahedral shape
and they are fully relaxed, before computing the addition energies
of methylamine and formate anions in different positions, to model
the process of surface passivation. Then the density of states of
all the clusters is computed, to study in particular the band gap
and the behavior of the so-called intragap states, which affect the
photophysical properties of the nanoparticles, also acting as trap
states for charge carriers. We confirm the strong relationship between
nanocluster off-stoichiometry and intragap states: such states can
be localized on the surface, in the bulk or delocalized over the nanoparticle,
according to the source of off-stoichiometry. The ability of different
ligands to eliminate the intragap states are tested and discussed,
also proposing nonstandard capping molecules