HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 236
C103 - The influence of titania morphology on dye loading for dye-sensitized solar
cells
Gabriella Di Carlo a , Daniela Caschera a , Marco Brucale a , Alessio Mezzi a , Giuseppe Calogero b ,
Gaetano Di Marco b , Giuseppina Padeletti a , Gabriel Maria Ingo a
a, ISMN-CNR, Via Salaria km 29300, Monterotondo Stazione (Rome), 00015, Italy
b, IPCF-CNR, Viale F. Stagno D’Alcontres 37, Messina, 98158, Italy
Dye-sensitized solar cells (DSSCs) are receiving increasing interest as a viable technology for
the conversion of sunlight into electricity [1]. In the DSSCs the dye, typically a ruthenium
bipyridyl complex, is absorbed on a titania substrate and extends the spectral sensitivity of the
photoelectrode. These devices are very promising systems for many different solar power
applications due to their low cost and lightweight [2].
The performance of the dye-titania photoanode are directly related to the processes that
occur at the dye/titania interface, since the photoinduced electron transfer from the excited
state of the dye to the conduction band of the titania is responsible for the production of the
photocurrent.
At present, in order to improve the efficiency of the photoanode, the attention has been
mainly focused on the chemical modification of the dye [3], whereas only a few studies have
been addressed on the improvement of titania film properties.
In the present study, N719 dye over titania films with significantly different morphology has
been investigated. In particular, titania films with a flat surface have been obtained using a solgel
procedure (TiSG). The roughness and the porosity of titania have been increased using a
soft template which allows producing a porous structure with a long range order (TiMS).
Finally, the morphology of the obtained samples has been compared with a reference titania
film, prepared with commercial titania using the well-known doctor-blade technique (TiDB).
The morphological properties of titania films and the N719 dye loading have been investigated
by atomic force microscopy and UV-vis spectroscopy, respectively. Moreover, X-ray
photoelectron spectroscopy (XPS) measurements have been performed to characterize the
chemical interaction between dye and titania. Our findings suggest that the mesoporous
structure improves the dye loading and that the morphological properties of titania film play a
key role. However, sol-gel and mesoporous titania films were deposited by spin-coating and
this procedure leads to coatings with a thickness which is significantly lower than doctor-blade
technique.
In order to improve the performance of the DSSCs, one of the main challenge is to increase
the dispersion and the loading of dye over titania. To this purpose, the development of high
surface area mesoporous titania films with a higher thickness is worthy of future
investigations.
References
[1] Graetzel, M. "Solar energy conversion by dye sensitized photovoltaic cells". Inorg. Chem. 44, 6841–6851 (2005).
[2] Gonçalves, L.M.; Bermudez, V.Z.; Ribeiro, H.A.; Mendes, A.M. "Dye-sensitized solar cells: A safe bet for the
future". Energy Environ. Sci. 1, 655-667 (2008).
[3] Nazeeruddin, Md.K.; Klein, C.; Liska, P.; Gratzel, M. " Synthesis of novel ruthenium sensitizers and their
application in dye-sensitized solar cells". Coord. Chem. Rev. 249, 1460–1467 (2005).
© SEFIN 2012