Anchoring porphyrin self-assembled dye sensitized solar cells: synthesis and photovoltaic application

Anchoring porphyrin, ZnPAc, featuring cyanoacetic acid group has been synthesized for application in a dye-sensitized solar cell. Capping layer dyes zinc meso-tetraphenyl porphyrin (ZnTPP) with anchoring porphyrin ZnPAc through axial coordination bonds of Zn-to-ligand self-assembles solar cell devices. With the introduction of cyanoacetic acid anchor, the higher electrons are effectively injected into the TiO₂ semiconductor surface. Thus, the ZnTPP-ZnPAc-based device has more short-circuit current (J_SC) compared with our previously reported ZnTPP-ZnPA-based solar cell. The ZnPA and ZnPAc porphyrin anchoring dyes maintain a broad absorption spectrum and also improve electron injection and lower charge recombination compared to our previous reports on organic molecule anchored dye W3. Hence, the ZnTPP-ZnPAc self-assembled dye has higher power conversion efficiency. The assembled modes were also verified by transmission electron microscopy (TEM). To understand ZnTPP-ZnPAc for photovoltaic performance trends, we have carried out charge extraction, transient photovoltage decay and electrochemical impedance spectroscopy analysis.