The effect of n-type phthalocyanine tin (IV) dichloride (SnCl(2)Pc) as cathode interfacial layer on the performance of poly[2-methoxy,5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction solar cells (ITO/PEDOT:PSS/MEH-PPV:PCBM/SnCl(2)Pc/LiF/Al) is investigated. Our results show that the integration of SnCl(2)Pc into the solar cell not only enhances the exciton dissociation efficiency due to the formation of additional MEH-PPV/SnCl(2)Pc exciton dissociation junction, but also improves the electron transport and collection due to the step-like electron injection barrier to cathode caused by SnCl(2)Pc interlayer. The incorporation of 6 nm thick SnCl(2)Pc interlayer leads to 15.7% improvement of the short circuit current density (J(SC)), which in turn results in 15.2% improvement of power conversion efficiency (eta) up to 2.49%. The results suggest that the employment of an n-type organic semiconductor like SnCl(2)Pc as an interlayer is a promising strategy to improve the device performance of polymer solar cells. (C) 2011 Elsevier B.V. All rights reserved.