Synthesis of asymmetric zinc phthalocyanine with bulky diphenylthiophenol substituents and its photovoltaic performance for dye-sensitized solar cells

Abstract

Abstract Asymmetric zinc phthalocyanine derivative ( Zn- tri -PcNc-9 ) bearing one carboxylic and six bulky diphenylthiophenol groups was synthesized as a sensitizer for dye-sensitized solar cells. The obtained Zn- tri -PcNc-9 exhibits strong and expanded Q-band absorption peak (at ∼741 nm) in the red/near-IR light (600–800 nm) range, and its photovoltaic performance in sensitizing TiO 2 -based solar cell can be significantly improved by using chenodeoxycholic acid (CDCA) as co-adsorbent due to the retarded charge recombination. Under an optimal sensitization condition, the corresponding solar cell exhibits an efficiency of 3.61%, which is improved by 144% as compared to the solar cell without CDCA. Moreover, Zn- tri -PcNc-9 -sensitized solar cell shows a maximum incident photo-to-current conversion efficiency of 31.6% at ∼730 nm, red-shifted by ∼20 nm as compared to that (∼710 nm) of its O-substituted analog ( Zn- tri -PcNc-8 ) bearing six diphenylphenoxy groups, suggesting an effective solution to expand the red/near-IR responsive range of the ZnPc-sensitized solar cell, and also demonstrating a possibility for future panchromatic sensitizing agents in dye-sensitized solar cells.