Hindawi Publishing Corporation International Journal of Photoenergy Volume 2013, Article ID 582786, 11 pages http://dx.doi.org/10.1155/2013/582786 Research Article Spectroscopic and Morphological Studies of Metal-Organic and Metal-Free Dyes onto Titania Films for Dye-Sensitized Solar Cells Gabriella Di Carlo, 1 Daniela Caschera, 1 Roberta G. Toro, 1 Cristina Riccucci, 1 Gabriel M. Ingo, 1 Giuseppina Padeletti, 1 Luisa De Marco, 2 Giuseppe Gigli, 2,3,4 Giovanna Pennesi, 5 Gloria Zanotti, 5 Anna M. Paoletti, 5 and Nicola Angelini 5 1 Institute for the Study of Nanostructured Materials (ISMN), CNR, Via Salaria km 29300, Monterotondo, 00015 Rome, Italy 2 Center for Biomolecular Nanotechnologies (CBN), Fondazione Istituto Italiano di Tecnologia, Energy Platform Via Barsanti, Arnesano, 73010 Lecce, Italy 3 National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano km 5, 73100 Lecce, Italy 4 Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via per Arnesano, 73100 Lecce, Italy 5 Institute of Structure of Matter (ISM), CNR, Via Salaria km 29300, Monterotondo, 00015 Rome, Italy Correspondence should be addressed to Gabriella Di Carlo; gabriella.dicarlo@ismn.cnr.it and Nicola Angelini; nicola.angelini@ism.cnr.it Received 13 July 2013; Accepted 27 August 2013 Academic Editor: Giuseppe Calogero Copyright © 2013 Gabriella Di Carlo et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We have investigated the spectroscopic behavior of three diferent sensitizers adsorbed onto titania thin ilms in order to gain information both on the electron transfer process from dye to titania and on the anchorage of the chromophore onto the semiconductor. We have examined by UV-Vis and luorescence spectroscopy the widely used ruthenium complex cis- di(thiocyanato)bis(2,2  -bipyridyl-4,4  -dicarboxylato)ruthenium(II) (N719), the more recently developed organic molecular 3-(5- (4-(diphenylamino)styryl)thiophen-2-yl)-2-cyanoacrylic acid (D5), and a push-pull zinc phthalocyanine sensitizer (ZnPc). hree type of titania ilms with diferent morphology, characterized by SEM and FT-IR measurement, were considered: a mesoporous transparent ilm deposited by spin-coating (TiMS), a semiopaque ilm deposited by doctor-blade from mesoporous titania (TiMS DB) and a semiopaque ilm deposited by doctor-blade form commercial P25 titania (P25 DB). he use of TiMS is responsible for the adsorption of a higher amount of dye since the mesoporous structure allows increasing the interfacial area between dye and titania. Moreover, the luorescence emission peak is weaker when the sensitizers are adsorbed onto TiMS. hese indings suggest that mesostructured ilms could be considered the most promising substrates to realize photoanodes with a fast electron transfer process. 1. Introduction Dye-sensitized solar cells (DSSCs) are receiving increasing attention during the last decades since they are considered a viable and cost-efective technology for the conversion of sunlight into electricity [1–3]. In these devices, metal- organic or metal-free dyes are chemically adsorbed onto a wide band gap semiconductor oxide [1–8]. he working principle of a DSSCs system is based on the photochemical and photophysical processes: upon photoexcitation of the dyes by visible light, electrons are excited from the ground state of the dye to its excited state, and then their injection can occur from the excited dye into the conduction band of the semiconductor. To achieve a high power conversion eiciency, the elec- tron injection process must be certain and faster than