New diketopyrrolopyrrole based D–A–D π-conjugated molecules: Synthesis, optical, electrochemical, morphological and photovoltaic properties

• New diketopyrrolopyrrole molecules with fused aromatic rings are presented.
• The influence of structural variation on the optical, electrochemical and film morphology are described.
• Preliminary photovoltaic devices of the as cast DPPs/PC71BM blends show similar performances with the literature data.

Two solution processable donor–acceptor, π-conjugated molecules that consist of diketopyrrolopyrrole (DPP) central acceptor unit with dibenzofuran (DPP-DBF) or acenaphtene (DPP-ACN) donor substituents, were prepared by Suzuki coupling reaction. The optical, electrochemical and film forming properties of these D–A–D molecules were investigated and used as active materials in bulk heterojunction solar cells.The molecules were characterized by UV–Vis spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), cyclic voltammetry (CV), atomic force microscopy (AFM). While the optical absorption and frontier orbital energy levels are less sensitive to the nature of the donor, the materials thermal properties, film morphology and the photovoltaic performances are significantly altered.

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