Synthesis of a Fully Conjugated Phthalocyanine-Diketopyrrolopyrrole-Phthalocyanine Triad as Low Band Gap Donor in Small Molecule Bulk Heterojunction Solar Cells

We describe the synthesis and photovoltaic properties of a fully conjugated phthalocyanine-diketopyrrolopyrrole-phthalocyanine triad (ZnPc-DPP-ZnPc) that presents strong visible absorption from 400 to 900 nm. The synthesis of the phthalocyanine with full conjugation to diketopyrrolopyrrole provides access to a new family of low band gap materials (<1.6 eV). Organic solar cells employing bulk heterojunction ZnPc-DPP-ZnPc:PC70BM films using MoO3 as anodic interfacial layer (IFL) show a power conversion efficiency of 1.04%. The power conversion efficiency decreases considerably by using PEDOT:PSS as interfacial layer as a consequence of protonation of the ZnPc.