Photovoltaic performance of PCBM analogs with different ester groups as acceptor in the polymer solar cells

A series of [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) analogs with different ester structures, such as isopropyl ester (F-1), sec-butyl ester (F-2), ethyl ester (F-3), 2-thiopheneethyl ester (F-4), phenethyl ester (F-5), and 4-methoxyphenethyl ester (F-6), were designed, synthesized, and evaluated for their photovoltaic performance. The optical, electrochemical, morphological, and photovoltaic properties of the molecules were characterized through UV-vis spectroscopy, cyclic voltammetry, and atomic force microscopy; then, the effects of different ester structures on these properties were investigated. Results showed that polymer solar cells (PSCs) with P3HT as a donor and F-1-F-6 as acceptors displayed different photovoltaic properties. The PSCs with F-1, F-2, and F-3 as acceptors showed higher photovoltaic performance than those with F-4, F-5 and F-6 as acceptors. Moreover, the power conversion efficiency of the former three PSCs exceeded or approached 3.0%, whereas that of the latter three PSCs was below 2.0%. Compared with PCBM, F-2 and F-3 with an aliphatic ester exhibited a slightly better photovoltaic performance, F-1 with isopropyl ester displayed similar photovoltaic properties, and other aromatic ring ester PCBM-like derivatives showed poorer photovoltaic performance. (C) 2015 Elsevier B.V. All rights reserved.