: In order to fabricate high performance polymer solar cells, donor:acceptor mixture must be prepared using a proper solvent. Since solubility of C60, as an electron acceptor material, is very limited in common solvents, finding a suitable solvent could considerably enhance the Poly(3-hexylthiophene) (P3HT):C60 based cell performance in terms of short circuit current (J_SC), fill factor (FF) and finally power conversion efficiency (PCE). The formation of C60 aggregates and donor material, i.e. Poly(3-hexylthiophene), crystallinity depend on the selection of proper solvent. These two factors influence the electrical and optical properties of the solar cell including absorption spectrum, exciton dissociation, mobility, etc. In this paper, 1,2-Dichlorobenzene (ODCB) and a mixture of 1-Chloronaphtalene and Chlorobenzene (Cl-naph:CB (1:33, v/v)) are chosen as two promising solvents for preparing P3HT:C60 film and a simulation was performed to understand how these solvents can influence the solar cell performance. We found that among 10 considered parameters, the most determinative ones are exciton generation rate (G), electron mobility (μ_n), hole mobility (μ_p) and the difference between P3HT HOMO and C60 LUMO energy level (E_g). Finally, the reason why the solar cell prepared with Cl-naph:CB performs even better than the annealed cell using ODCB is explained using simulation results.

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