Liquid Crystals of Phthalocyanine-Fullerene Dyads Exhibiting Homeotropic Alignment and Spiranthes-like Supramolecular Structure Useful for Solar Cells

If liquid crystals of phthalocyanine-fullerene (Pc-C₆₀) dyads would exhibit homeotropic alignment at r.t., they would be very useful for the application to solar cells. Hence, we have synthesized nine novel Pc-C₆₀ dyads, (C_nS)₆PcCu-C_m-C₆₀ (n = 14, 16, 18; m = 8, 10, 12), to investigate whether they would exhibit perfect homeotropic alignment at r.t. by changing lengths of the peripheral alkylthio chains (C_n) and the spacer chain (C_m) between Pc and C₆₀. As a result, each of them exhibited a hexagonal ordered columnar (Col_ho) mesophase and the Col_ho mesophase for n = 14 and m = 8, 10, 12, showed perfect homeotropic alignment in a wide temperature region from r.t. to clearing point. Moreover, the Col_ho mesophases exhibited spiranthes-like supramolecular structure, which is compatible with one-dimensional nano-array expecting the high conversion efficiency of solar cells.