Hindawi Publishing Corporation International Journal of Photoenergy Volume 2012, Article ID 216780, 11 pages doi:10.1155/2012/216780 Research Article Electric Characterization and Modeling of Microfluidic-Based Dye-Sensitized Solar Cell Adriano Sacco, 1, 2 Andrea Lamberti, 1, 2 Marzia Quaglio, 1 Stefano Bianco, 1 Elena Tresso, 1, 2 Anca-Luiza Alexe-Ionescu, 1, 3 and Candido F. Pirri 1, 2 1 Center for Space Human Robotics @Polito, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino, Italy 2 Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy 3 Faculty of Applied Sciences, University Politehnica of Bucharest, Splaiul Independentei 313, 060042 Bucharest, Romania Correspondence should be addressed to Stefano Bianco, stefano.bianco@iit.it Received 3 November 2011; Accepted 4 January 2012 Academic Editor: Latika Menon Copyright © 2012 Adriano Sacco et al. This 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. The electric response to an external periodic voltage of small amplitude of dye-sensitized solar cells (DSCs) made up with an alternative architecture has been investigated. DSCs have been fabricated with a reversible sealing structure, based on microfluidic concepts, with a precise control on the geometric parameters of the active chamber. Cells with different electrolyte thicknesses have been characterized, without varying the thickness of the TiO 2 layer, both under illumination and in dark conditions. Measurements of the electric impedance have been performed in the presence of an external bias ranging from 0 V to 0.8 V. The experimental data have been analyzed in terms of a transmission line model, with two transport channels. The results show that the photovoltaic performances of the microfluidic cell are comparable with those obtained in irreversibly sealed structures, actually demonstrating the reliability of the proposed device. 1. Introduction Since the first paper of O’Regan and Gr¨ atzel [1], dye- sensitized solar cells (DSCs) have been widely investi- gated as one of the most promising candidates for the next-generation solar devices with low production costs, simple fabrication process, and good efficiency in energy conversion. It is easy to obtain DSC samples employing commercially available materials and simple process steps, nevertheless, the performances are strongly dependent on the material quality and the fabrication procedure. Newly implemented manufacturing solutions such as advanced print screen techniques, electrolyte filling, dye profiling, and sealing machines have been reported for obtaining small laboratory DSC with efficiency up to 10%, good stability, and reproducibility [2–6]. The present DSC research and development focus on finding materials and manufacturing techniques for higher conversion efficiency, lower costs, and longer operating lifetime. In this process, the understanding of the influence of materials and com- ponents on the overall efficiency is essential. Experimental measurements provide a basis for identifying the factors mostly limiting the efficiency of a DSC. Furthermore, when coupled to mathematical models, they can provide a quantitative understanding of the device’s physics [7]. Also, numerous papers have been published on modeling and interpreting the results obtained from electrochemical impedance spectroscopy (EIS) measurements [7–16]. Several papers have been published suggesting the best fabrication procedure of the cells [2, 17, 18] and, moreover, in the papers reporting experimentalresults, the procedure used to obtain small laboratory cells is quite always illustrated in details. Even if sometimes a simple-clips closure has been chosen, the use of hot-melt sealants is generally adopted for closure and protection from the environment. For research purposes, this can be somewhat limiting. Indeed, some of the fabrication steps, as dye adsorption and electrolyte filling, are often performed without any direct/active control, being difficult to ensure reproducibility and reliability while fabricating a large number of cells. Both during experiments and after them, the cell, being irreversibly sealed, does not