Enhancement of short current density in polymer solar cells with phthalocyanine tin (IV) dichloride as interfacial layer

The effect of n-type phthalocyanine tin (IV) dichloride (SnCl2Pc) 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/SnCl2Pc/LiF/Al) is investigated. Our results show that the integration of SnCl2Pc into the solar cell not only enhances the exciton dissociation efficiency due to the formation of additional MEH-PPV/SnCl2Pc exciton dissociation junction, but also improves the electron transport and collection due to the step-like electron injection barrier to cathode caused by SnCl2Pc interlayer. The incorporation of 6 nm thick SnCl2Pc interlayer leads to 15.7% improvement of the short circuit current density (JSC), which in turn results in 15.2% improvement of power conversion efficiency (η) up to 2.49%. The results suggest that the employment of an n-type organic semiconductor like SnCl2Pc as an interlayer is a promising strategy to improve the device performance of polymer solar cells.