Research Article Numerical Procedure for Optimizing Dye-Sensitized Solar Cells Mihai Razvan Mitroi, 1 Laurentiu Fara, 1,2 and Magdalena Lidia Ciurea 2,3 1 University Politehnica of Bucharest, 313 Splaiul Independentei, 060042 Bucharest, Romania 2 Academy of Romanian Scientists, 54 Splaiul Independentei, 050094 Bucharest, Romania 3 National Institute of Materials Physics, 105 bis Atomistilor Street, P.O. Box MG-7, 077125 Magurele, Romania Correspondence should be addressed to Magdalena Lidia Ciurea; ciurea@infm.ro Received 23 July 2013; Revised 13 November 2013; Accepted 29 November 2013; Published 5 January 2014 Academic Editor: Hyeong-Ho Park Copyright © 2014 Mihai Razvan Mitroi et al. Tis 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 propose a numerical procedure consisting of a simplifed physical model and a numerical method with the aim of optimizing the performance parameters of dye-sensitized solar cells (DSSCs). We calculate the real rate of absorbed photons (in the dye spectral range)  real () by introducing a factor <1 in order to simplify the light absorption and refection on TCO electrode. We consider the electrical transport to be purely difusive and the recombination process only to occur between electrons from the TiO 2 conduction band and anions from the electrolyte. Te used numerical method permits solving the system of diferential equations resulting from the physical model. We apply the proposed numerical procedure on a classical DSSC based on Ruthenium dye in order to validate it. For this, we simulate the J -V characteristics and calculate the main parameters: short-circuit current density  sc , open circuit voltage  oc , fll factor FF, and power conversion efciency . We analyze the infuence of the nature of semiconductor (TiO 2 ) and dye and also the infuence of diferent technological parameters on the performance parameters of DSSCs. Te obtained results show that the proposed numerical procedure is suitable for developing a numerical simulation platform for improving the DSSCs performance by choosing the optimal parameters. 1. Introduction Te technology and materials used for the third generation solar cells give the opportunity to obtain cells with high efciency [1–5]. Te solar cells based on dye-sensitized nano- structure with mesoporous metal oxides (DSSCs) have attracted considerable attention since the work of O’Regan and Gr¨ atzel [6], their manufacturing being environment- friendly and energy-efcient [1, 7]. Up to now, certifed ef- ciencies over 10% under standard conditions or even higher (12,4%) at the laboratory scale were reported [7–10]. Based on the low cost of materials and the simplicity of fabrication process, DSSC can have lower fabrication costs than con- ventional silicon-based solar cells. Taking into account this advantage, the improvement of DSSC parameters for making them widely used appears as a strong necessity. Further optimization of the DSSC parameters requires a better correlation between interrelated processes of transport and accumulation of electrons in the mesoporous oxide phase and recombination of electrons with electron acceptors [11]. In order to understand the diferent processes governing the DSSC’s mode of operation and to enhance the DSSCs performance, modeling of processes and numerical simu- lation of the cells were carried out [12–23]. Te thickness, morphology (particle diameter and porosity) for the TiO 2 layer, electron mobility and recombination rate (electron life- time), absorption spectrum of the dye, thickness and material quality of transparent conductive oxide (TCO) layers and the used electrolyte determine the - characteristics [17, 18, 20–22, 24]. Consequently, the extracted parameters from simulation, the short-circuit current density  sc , the open circuit voltage  oc , the fll factor FF, and the power conversion efciency  were analyzed. In the present paper, we propose a numerical procedure for optimizing the DSSCs consisting of a simplifed physical model and a numerical method capable of solving the system of diferential equations resulted from the physical model. We applied this proposed procedure on a DSSC with Ru dye Hindawi Publishing Corporation Journal of Nanomaterials Volume 2014, Article ID 378981, 6 pages http://dx.doi.org/10.1155/2014/378981