Dye sensitized mesoporous thick TiO
2
layers deposited by grazing incidence reactive
sputtering methods assisted by local oxidation
Salvatore Sanzaro
1,2*
, Emanuele Smecca
1
, Giovanna Pellegrino
1
, Corrado Bongiorno
1
,
Fortunato Neri
2
, Graziella Malandrino
3
, Maria Rita Catalano
3
, Luisa De Marco
4,5
, Rosabianca
Iacobellis
4,5
, Giovanni Mannino
1
, Antonino La Magna
1
and Alessandra Alberti
1*
1
CNR-IMM Zona industriale, Strada VIII n° 5, 95121, Catania, Italy.
2
Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra,
Università degli Studi di Messina, Viale F. Stagno d’Alcontres, 31 - 98166 Messina, Italy
3
Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6,
95125 Catania, Italy.
4
Center for Biomolecular Nanotechnology (CBN) Fondazione Istituto Italiano di Tecnologia,
Via Barsanti 1, 73010, Arnesano, Italy.
5
Dipartimento di Ingegneria dell'Innovazione, Università del Salento, via per Monteroni.
73100, Lecce, Italy.
We propose a new method based on physical deposition concepts for up-scalable, low
temperature, reliable, contamination-free TiO
2
materials with multi-scale porosity ranging
form nano to meso dimensionalities. The multi-scale-porosity material is conceived to be, in
prospective, a multipurpose platform able to merge different functionalities. To this intent, we
combined in a unique material 1) an intra-grain nano-porosity (1-5nm) offered by the
application of the Thornton’s conditions and 2) an extra-grain meso-porosity (10-50 nm)
arising from the use of a modified sputtering approach. The deposition procedure combines a
Titanium flux coming from an-off-axis source with an oxidation process localized where the
ad-atoms land (substrate), far from the Ti source. Differently from TiO
2
layers sputtered in
conventional ways, the porosity level in our mesoporous materials was preserved even after
annealing up to 500°C, with the TiO
2
rods arranged in the anatase structure.
As proof-of-concept to demonstrate the applicative value of our material, a high molecular
infiltration and chemisorption on the TiO
2
free-surfaces were proved with density as high as
1
10
20
molecules/cm
3
, superior with respect to reference sputtered materials.
The functionality of the material was finally tested in prototype thin DSCs. Our prototype
solar cells represent the first demonstration of a sputtered TiO
2
anatase meso-material with
capability comparable to commercial TiO
2
products for DSSC, with the added-value of being
implementable on low cost substrates if treated at 200°C
Based on the demonstrated attitude of the material to be functionalized, its surface activity can
be in principle differently modified using other kind of molecules or gas species or even nano-
materials such as hybrid perovskites to extend the range of application.
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