Columbia International Publishing Journal of Modeling, Simulation, Identification and Control (2013) Vol. 1 No. 3 pp. 105-114 doi:10.7726/jmsic.2013.1008 Research Article ______________________________________________________________________________________________________________________________ *Corresponding e-mail: mustapha.merad@gmail.com 1* Unit of Research Materials & Renewable Energies, University Abou baker Belkaid of Tlemcen, Algeria 2 Laboratory of Study and Development of Semiconductors and Dielectric Materials, University Amar Telidji of Laghouat Algeria 105 Concrete Optimization and Modeling of Organic Tandem Solar Cells using Series Resistance, Temperature and Optical Band Gap Mustapha Réda Merad Boudia 1* , Ali Cheknane 2 , Boumediene Benyoucef 1 , and Abdelmadjid Ferouani 1 Received 7 July 2013; Published online 3 August 2013 © The author(s) 2013. Published with open access at www.uscip.org Abstract A comparative study of two methods for extracting solar cell parameters of single and two-diode lumped- circuit model is presented. These parameters are usually the saturation current, the series resistance, the ideality factor, the shunt resistance and the photocurrent. It is found that the influence of the distributed series resistance on electrical characteristics can be described numerically by the application of the two models to Tandem organic solar cells. A description of the efficiency fill factor open circuit voltage and sort circuit current on the devices are marked with series resistance, optical band gap and atemperature .This approach allows one to obtain a set of parameters which is reasonable and representative of the physical system. Keywords: Tandem organic solar cell; Temperature; Optical band gap; Optimization and Series resistance 1. Introduction Organic photovoltaic technology allows reducing the production costs of solar energy. A considerable effort has led very recently to achieve power conversion efficiencies near 10% in the case of bulk-heterojunction and tandem solar cell structures (Green et al 2012)- (Kirchartz T et al 2009a). Although several limiting factors have been studied, and their detrimental effects quantified (I.M. Dharmadasa, 2009), further improvements need for detailed understanding of specific phenomena.