In order to fabricate high performance polymer solar cells, donor:acceptor mixture must be prepared using a proper solvent. Since solubility of C60, as a truly cost effective acceptor, is very limited in common solvents, finding a suitable solvent can enhance the Poly(3-hexylthiophene):C60 (P3HT:C60) based solar cell performance in terms of short circuit current (JSC), fill factor (FF) and consequently power conversion efficiency (PCE). The formation of C60 aggregates and P3HT crystallinity depend on the selection of proper solvent. These two factors influence several electrical and optical properties of the cell. In this work, 1,2-Dichlorobenzene (ODCB), the most common solvent, and a mixture of 1-Chloronaphtalene and Chlorobenzene and 1- Methylnaphtalene and Chlorobenzene are chosen as two alternative solvents for preparing P3HT:C60 films and simulation is performed to understand how these solvents influence the solar cell behavior. The performance of a P3HT:PCBM cell prepared with ODCB is also considered for comparison. A numerical model is employed to simulate the operation of different cells mentioned. In order to model the finite slope of I-V curve in large forward bias, the effect of voltage dependent series resistance is also considered. A minimizing algorithm is employed To determine the estimated values of unknown code input parameters, minimizing the fitting error of simulated and experimental I-V curves. Comparing the numerical model with conventional one shows that traditional models may not be accurate enough for analyzing organic photovoltaics. It is also shown that every 20% increase in G results in about 20% JSC enhancement; this amount of increase is easily obtained using a proper solvent. Another crucial factor in determining solar cell performance is mobility which considerably depends on the solvent. This work provides experimentalists with an idea of how they should select a solvent as a determinative material in solution-processed based solar cells. The results can also be generalized to find a proper solvent for other active layer materials.

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