Integration of an M-phthalocyanine layer into solution-processed organic photovoltaic cells for improved spectral coverage

Photovoltaic devices made from blended poly(3,3‴-didodecylquaterthiophene) (PQT-12) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) incorporating an additional interlayer of M-phthalocyanine (M-Pc) have been characterized using current–voltage response, UV–visible absorption and external quantum efficiency. The introduction of H2Pc, CuPc, ClInPc or TiOPc layers improves device performance compared to conventional bulk-heterojunction PQT-12:PCBM cells without M-Pc. Devices with M-Pc show increased absorption and free charge generation at longer wavelengths and have higher open circuit voltage. Polymorphic changes from solvent interaction are observed in TiOPc films during fabrication. Power conversion efficiencies of 0.79% are achieved for this modified bulk-heterojunction solar cell.