Synthesis and photovoltaic properties of the copolymers containing zinc porphyrin derivatives as pendant groups

•Zinc-porphyrin was introduced into copolymers as pendant group.•Four copolymers with DPP and zinc-porphyrin (ZP) derivatives were synthesized.•Copolymer P(ZP-BT-DPP4) gave a power conversion efficiency of 2.44%.

A series of copolymers containing zinc porphyrin (ZP) derivatives as pendant groups and diketopyrrolopyrrole (DPP) as electron-withdrawing units were designed and synthesized by Stille-coupling polymerization. The introduction of zinc porphyrin derivatives enhances the light-harvesting capability and leads to a complementary absorption at short wavelength band. The absorption of the copolymers can be well-tuned by varying the ratio of zinc porphyrin derivatives and DPP units. The results indicated that copolymer P(ZP-BT-DPP4) with ZP/DPP ratio of 1:4 showed an strong absorption in the range of 400-900 nm. The power conversion efficiency (PCE) of 2.44% with an increased Jsc of 6.14 mA/cm2 was achieved due to the better light-harvesting ability and suitable active film morphology.

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