Weakly Conjugated Hybrid Zinc Porphyrin Sensitizers for Solid-State Dye-Sensitized Solar Cells

Molecularly engineered weakly conjugated hybrid porphyrin systems are presented as efficient sensitizers for solid-state dye-sensitized solar cells. By incorporating the quinolizino acridine and triazatruxene based unit as the secondary light-harvester as well as electron-donating group at the meso-position of the porphyrin core, the power conversion efficiencies of 4.5% and 5.1% are demonstrated in the solid-state devices containing 2,2',7,7'-tetrakis (N,N-di-p-methoxyphenylamine)-9,9'-spiro bifluorene as hole transporting material. The photovoltaic performance of the triazatruxene donor based porphyrin sensitizer is better than that of the previously published porphyrin molecules exhibiting strongly conjugated push-pull structure. The effect of molecular structure on the optical and electrochemical properties, the dynamics of charge extraction, as well as the photovoltaic performance are systematically investigated, which offers a new design strategy for further refinement of porphyrin molecules.