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Journal of Chemical Technology and Applications | Volume 2
Annual Spring Conference and Expo on
April 04-05, 2018 | Miami, USA
Chemical Engineering: From
Materials Engineering to Nanotechnology
allied
academies
O
ne of the emerging applications exploring the
potentialities of fluorescent nanomaterials is related to
light emitting technologies. In particular for the realization
of practical light-emitting diodes and large-area displays,
semiconductor nanomaterials may overcome many
issues of such challenging technologies. A critical aspect
of semiconductor nano scaled materials is related to the
large Coulomb interaction between electrons and holes,
and their strong spatial confinement, with respect to their
bulk analogues. When the size is reduced to levels smaller
than the exciton Bohr radius, size-dependent absorption
and emission properties develop. Upon formation of
excitons within quantum dots (QDs) through optical or
electrical processes, Coulomb interactions play a key role
in subsequently determining their radiative and non-
radiative decay rates, fluorescence quantum yields, multi-
exciton generation and its decay. Appropriate engineering
of QDs, through the colloidal synthesis of core/shell
heterostructures, has emerged as the most facile manner
to gain control of these Coulomb processes. The strong
electronic coupling between the core and shell in core/shell
QDs ensures that the electronic structure, composition and
thickness of the shell must be considered in parallel with the
properties of the core in order to predictably manipulate the
electron and hole probability densities to obtain the desired
optoelectronic characteristics. This spatial control of carriers
affects the direct Coulomb interaction between electrons
and holes, but also influences the rate and carrier selectivity
of trapping at surface and, possibly, interface defects. The
latter is highly dependent on the core/shell structure,
for which lattice mismatch between materials must be
carefully managed to avoid defect formation stemming
from excessive interfacial stress. The above structural and
electronic factors define the dynamics of single and multi
excitons in QDs, which directly influences aspects such as
recombination lifetimes, luminescence efficiency and optical
gain properties. Considering the importance of each of these
properties for light emitting applications, in this presentation
we compare different approaches for the enhancement of
light emission quality in terms of high fluorescence efficiency,
high color quality, enhanced photostability under prolonged
irradiation and easy implementation of solution processable
methodologies. All these excellent features make the use of
QDs materials a promising way for the realization of optically
and electrically pumped light emitting devices.
Speaker Biography
Raffaella Signorini Since October 2015 working as an Associate Professor in Physical
Chemistry at the Department of Chemical Sciences of the University of Padova. Her
major research interests focus on non-linear optical spectroscopies and nanomaterials.
The research activity spans from the NLO characterization of chromophores, including
reverse saturable absorption, two-photon absorption and emission, to the realization
of compact devices, like optical limiters and integrated lasers, and micro-fabrication
e:
raffaella.signorini@unipd.itEngineering of semiconductor quantum dots for light emitting applications
Raffaella Signorini
1
, Francesco Todescato
1
, Ilaria Fortunati
1
, Alessandro Minotto
1
, Jacek J Jasieniak
2
and
Renato Bozio
1
1
University of Padova, Italy
2
Monash University, Australia