Nano Research & Applications

Semiconductor quantum dots for light emitting applications

17^th Edition of International Conference on Emerging Trends in Materials Science and Nanotechnology
April 26-27, 2018 Rome, Italy

Raffaella Signorini, Francesco Todescato, Ilaria Fortunati, Alessandro Minotto, Jacek J Jasieniak and Renato Bozio

INSTM - University of Padova, Italy Monash University, Australia

ScientificTracks Abstracts: Nano Res Appl

DOI: 10.21767/2471-9838-C1-008

Abstract

One 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 nanoscaled 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 nonradiative 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 interfaces 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 Recent Publications 1. Minotto A, Todescato F, Fortunati I, Signorini R, Jasieniak J J and Bozio R (2014) Role of Core-Shell Interfaces on Exciton Recombination in CdSe-CdxZn1xS Quantum Dots. The Journal of Physical Chemistry C 118(41):24117-24126. 2. Fede C, Fortunati I,Weber W, Rossetto N, Bertasi F, Petrelli L, Guidolin D, Signorini R, De Caro R, Albertin G and Ferrante C (2015) Evaluation of gold nanoparticles toxicity towards human endothelial cells under static and flow conditions. Microvascular Research 97:147- 155. 3. Vittadello L, Zaltron A, Argiolas N, Bazzan M, Rossetto N and Signorini R (2016) Photorefractive direct laser writing. Journal of Physics D: Applied Physics 49:125103-125111.4.. Todescato F, Fortunati I, Minotto A, Signorini R, Jasieniak J J and Bozio R (2016) Engineering of semiconductor nanocrystals for light emitting applications. Materials 9(8):672. 5. Scian C, Todescato F, Signorini R, Agnoli S, Cesca T, Bozio R and Mattei G (2017) Oxidation effects on the SERS response of silver nanoprism arrays. RSC Advances 7(1):369- -378.

Biography

Raffaella Signorini has been working as an Associate Professor in Physical Chemistry at the Department of Chemical Sciences of the University of Pa
dova since October 2015. Her research activity: (i) Characterization of the optical properties of chromophores characterized by reverse saturable absorption (RSA) and two photon absorption (TPA), and development of an optical limiting device capable to protect from pulsed and CW laser radiation in a wide frequency band; (ii) Investigation of the up-converted stimulated emission of chromophores in suitable laser cavities and development of an integrated laser device; (iii) Characterization of the two photon induced fluorescence of organic multipolar chromophores; (iv) Investigation of hybrid sol- gel materials properties, displaying photocatalitic activity; (v) Micro and sub-micro fabrication via two photon induced polymerization of polymeric and sol-gel materials; (vi) Realization and characterization of plasmonic nanostructures for sensing applications. She is an author of almost fifty papers on international journals and books, and two patents.

Email:raffaella.signorini@unipd.it