Solution-processed boron subphthalocyanine derivatives as acceptors for organic bulk-heterojunction solar cells

We report the fabrication of solution-processed bulk heterojunction devices from subphthalocyanine (SubPc) units as the acceptor component and conventional polymeric donor materials such as MEH-PPV, P3HT and PTB7. The high solubility of the SubPc derivatives facilitated the formation of efficient donor/acceptor networks and provided power conversion efficiencies of 0.4% with MEH-PPV, 1.1% with P3HT and 3.5% with PTB7. A clear contribution of photon harvesting by the acceptor was identified from the external quantum efficiency spectra. Analysis of the current-voltage characteristics and photoluminescence quenching revealed trap-assisted and geminate recombination as a loss mechanism. Our results show that solution-processable SubPcs are a promising alternative to fullerenes for polymer solar cells.