Non-peripheral octahexylphthalocyanine doping effects in bulk heterojunction polymer solar cells

The improvement of long-wavelength sensitivity in bulk heterojunction organic thin-film solar cells based on poly(3-hexylthiophene) (P3HT) by the addition of the soluble phthalocyanine derivative, 1,4,8,11,15,18,22,25-octahexylphthalocyanine (C6PcH2) is reported. C6PcH2 possesses near-infrared absorption and can be mixed with a P3HT:1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM) bulk heterojunction active layer. By doping C6PcH2, the photosensitivity in the long-wavelength region was improved, and the energy conversion efficiency reached 3.0% at a composition ratio of P3HT:C6PcH2:PCBM = 10:3:10. We discuss the principle of photoconversion in the bulk heterojunction solar cell based on the P3HT:C6PcH2:PCBM active layer by taking into consideration the existence of both highly ordered P3HT domains and hexagonal columnar structures of C6PcH2, and the microphase separation of P3HT and C6PcH2 in the active layer.

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► The improvement of long-wavelength sensitivity in polymer solar cells is reported.
► By doping phthalocyanine derivative (C6PcH2), the photosensitivity in the long-wavelength region was improved.
► The bulk heterojunction was composed of both highly ordered P3HT domains and hexagonal columnar structures of C6PcH2.
► We have discussed the mechanisms of photoconversion in the P3HT:C6PcH2:PCBM solar cell.