book of abstracts - IM2NP

A B S T R A C T S THURSDAY, JULY 1 N A N O S E A 2 0 1 0
9H40-10H00
Optoelectronic properties of porphyrines oligomers: an ab-initio study.
M.Palummo (a), C. Hogan (a), F. Sottile (b), A.Rubio(c) ((a) ETSF, Fisica, Univ. Tor Vergata
Via della Ricerca Scientifica I, Rome Italy, (b) ETSF, Ecole Polytecnique, CEA/CNRS Palaiseau France, (c) ETSF,
Dpto. Fisica de Materials, Univ. del Pais Vasco, San Sebastian Spain).maurizia.palummo@roma2.infn.it,
conor.hogan@roma2.infn.it, francesco.sottile@polytechnique.fr, angel.rubio@ehu.es
Porphyrin oligomers (short chains of porphyrins covalently linked by small molecular bridges) are of great
interest nowadays for biosensors and optoelectronic industry. Thanks to the pi-coniugationthey are
characterized by high polarizabilities, large oscillator strenghts and low electronic transitions. For these
reasons they show much potential for efficient organic solar cells.
These properties depend sensitively on particular structural components such as functional groups,the chain
length and the type of central metal atom and the molecular bridge. All these factorsdetermine the formation
and a different spatial localization of excitons.In this presentation we describe ab-initio calculations [1] of
electronic and optical properties of free-base and Zinc porphyrines systems both as isolated molecules,
oligomers and molecular crystals.The electronic excited states are obtained using the GW approach needed
for a correct computationof the quasi-particle states, while the optical spectra and the excitonic properties are
computedsolving the Bethe-Salpeter equation which fully describes the electron-hole coupled dynamics
[2].A discussion about the optical features and the change of the exciton charactermoving from isolated
molecules [3] to oligomers [4], or molecular crystals, will be done.
[1] A.Marini, C. Hogan, M. Gruning, D. Varsano Comp. Phys. Comm. 180 (2009) 1392–140
[2] G. Onida, L. Reining, A. Rubio, Rev. Mod. Phys. 74, 601 (2002) and references therein.
[3] M. Palummo, C. Hogan, F. Sottile, P. Bagala', A. Rubio J. Chem. Phys. 131, 084102 (2009)
[4] C. Hogan, M. Palummo, F. Sottile, A. Rubio, preprint
10H00-10H20
Self-assembly of Tetrathiafulvalene on Surfaces studying the Charge Transfer
Phenomena.
C. Simäo, M. Mas-Torrent, C. Rovira (ICMAB-CSIC., Campus de la UAB, 08193 Bellaterra,
Barcelona, Spain). csimao@icmab.es
1 – Introduction
The ultimate goal of molecular bottom-up approaches is to employ functional building blocks to construct
nanometer scale devices addressed to specific applications. Furthermore, for practical device implementation
the immobilization of functional molecules on suitable surfaces is also often required. In this work, we
describe the preparation of self-assembly monolayers (SAMs) of electroactive molecules in order to have a
molecular switch on a surface.
2 – Abstract
The molecules employed were tetrathiafulvalenes (TTFs) derivatives, which are compounds that present two
accessible redox states that exhibit different optical and magnetic properties that can be used as read-out
responses. This bistability is required for fabricating molecular switches since, in this way, these systems can
present „ON‟ and „OFF‟ states. The approach employed here is to construct a molecular switch on a surface
is to fabricate a SAM with these bistable molecules on indium-tin oxide (ITO), which is a transparent
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