Rationalizing the electronic properties of two classes of push–pull DSSC sensitizers based on Zn(II) di- or tetrarylporphyrinates substituted in meso or beta-pyrrolic positions: an electrochemical investigation
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Data di Pubblicazione:
2013
Citazione:
Rationalizing the electronic properties of two classes of push–pull DSSC sensitizers based on Zn(II) di- or tetrarylporphyrinates substituted in meso or beta-pyrrolic positions: an electrochemical investigation / A. Orbelli Biroli, F. Tessore, M. Pizzotti, G. Di Carlo, A. Abbotto, F. De Angelis, P.R. Mussini. ((Intervento presentato al 46. convegno Heyrovský Discussion tenutosi a Třešť (Czech Republic) nel 2013.
Abstract:
Push–pull Zn(II)-porphyrinates have recently shown attracting performances as
light harvesting systems in dye-sensitized solar cells (DSSCs). To fully exploit their
intrinsically high efficiency it is important to finely tune their HOMO and LUMO levels,
which can be achieved by proper choice of the push and pull substituents. Of course
such target-oriented molecular design requires the availability of reliable relationships
between molecular structure and electronic properties; therefore we have carried out
a detailed electrochemical investigation, also supported by spectroscopy and
theoretical computations, on a wide, systematic range of Zn(II)-porphyrinates:
(a) a family of 5,15-meso substituted ones with phenylethynyl linkers, including a
first "benchmark" symmetric series carrying on the opposite terminals the same
substituent (N(CH3)2, OCH3, COOCH3, COOH, NO2); and a second push–pull one,
with the terminal positions carrying one donor and one acceptor group belonging to
the series above. Moreover, two suitably modified porphyrins allowed evaluation of
the effects of (i) the presence or absence of the phenyl group in the linker between
the porphyrin core and the acceptor group, and (ii) the effect of perfluorination on the
same phenyl group;
(b) a family of mono and, for the first time, disubstituted push-pull ZnIIporphyrinates
bearing a variety of ethynyl-phenyl moieties in β-pyrrolic position,
which were compared with their meso analogues, producing evidence that, although
the HOMO-LUMO energy gap of the meso substituted push-pull dyes is lower, the β
mono or disubstituted push-pull porphyrinic dyes show comparable or better
efficiencies when acting as sensitizers in DSSCs, possibly on account of a more
facile charge injection into TiO2.
A rationalization scheme is proposed concerning relationship between structure
and redox properties, affording inter alia interesting clues on the different localization
of the redox centres and the effective conjugation between the porphyrin core and
the side chains as a function of the molecular design.
References:
[1] P. R. Mussini, A. Orbelli Biroli, F. Tessore, M. Pizzotti, C. Biaggic, G. Di Carlo, M.
G. Lobello, F. De Angelis, Electrochimica Acta 85 (2012) 509– 523
[2] G. Di Carlo, A. Orbelli Biroli, M. Pizzotti, F. Tessore, V. Trifiletti, R. Ruffo, A.
Abbotto, A. Amat, F. De Angelis, P. R. Mussini, Chemistry-a European Journal, in
press (2013).
Tipologia IRIS:
14 - Intervento a convegno non pubblicato
Elenco autori:
A. Orbelli Biroli, F. Tessore, M. Pizzotti, G. Di Carlo, A. Abbotto, F. De Angelis, P.R. Mussini
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