Photovoltaic Properties of 1,4,8,11,15,18,22,25-Octaalkylphthalocyanine Doped Polymer Bulk Heterojunction Solar Cells

The effects of doping a liquid crystalline phthalocyanine derivative, 1,4,8,11,15,18,22,25-octaalkylphthalocyanine (CnPcH₂, n = 6, 7), into bulk heterojunction organic thin-film solar cells based on poly(3-hexylthiophene) (P3HT) and 1-(3-methoxy-carbonyl)-propyl-1-1-phenyl-(6,6)C61 (PCBM) were studied. The absorbance spectra and external quantum efficiency spectra in the near-infrared region corresponding to the Q-band of CnPcH₂ were improved by doping C6PcH₂ or C7PcH₂. On the basis of the characteristics of CnPcH₂, obtained optical properties, and results of analysis of X-ray diffraction of the composite films of P3HT:CnPcH₂:PCBM, we discussed the photovoltaic properties of solar cells with CnPcH₂ by taking the micro phase separation in the active layers into consideration.