Charging Characteristics of Lithium Ion Battery Using Semi-Solar Modules of Polymer:Fullerene Solar Cells

The combination of lithium ion battery (LIB) and organic (polymer) solar cells is expected to deliver versatile self-rechargeable portable energy sources, but less attention has been paid to the charging characteristics of LIB-using polymer solar cells. Here we demonstrate that the LIB packs, which were prepared by using lithium cobalt oxide (LiCoO2) and graphite as a cathode and an anode, respectively, can be effectively charged by semi-solar modules of polymer:fullerene solar cells, of which bulk heterojunction (BHJ) layers are composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). Results showed that the performance of semi-solar modules was not much degraded by connecting four single solar cells in series or in parallel, but their output power density was noticeably reduced by extending the number of single cells up to eight. The charging test disclosed that the output current density is of importance to speed up the LIB charging at the same output voltage.