Asymmetric phthalocyanine derivatives containing 4-carboxyphenyl substituents for dye-sensitized solar cells

摘要

The synthesis of two asymmetrical zinc (II) phthalocyanines (ZnPcs) containing 4-carboxyphenyl and 3-thienyl or 5'-hexyl-2,2'-bithiophene substituent was described. These Zinc Phthalocyanines were synthesized by a statistical condensation reaction between two different phthalonitriles. Each of the phthalonitrile precursors was accomplished by the Suzuki-Miyaura cross-coupling reactions with the aryliodide and corresponding boronic acids. The ZnPc dyes were characterized by MALDI-MS, FT-IR, ~1H NMR, UV-Vis, fluorescence and cyclic voltammetry methods. Compared with 3-thienyl substituted ZnPc-1 dye, the Q-band absorption of 5'-Hexyl-2,2'-bithiophene substituted ZnPc-2 was red-shifted by 13 nm because of the extension of π-system. The ZnPc dyes were used as sensitizers in dye-sensitized solar cells (DSSCs). ZnPc-2 sensitized solar cell devices using a 7 (transparent) + 5 (scattering) nm thin TiO2 layer yielded a short-circuit photocurrent density of 3.81 mA/cm~2, an open-circuit voltage of 500 mV, and a fill factor of 0.59, corresponding to an overall conversion efficiency of 1.12% under standard AM 1.5 sun light.