Cosensitization and photoelectric conversion of a nanostructured TiO 2 electrode with tetrasulfonated porphyrins
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Huihua Deng, Zuhong Lu, Haifang Mao and Yaochun Shen
Abstract
The cosensitization of a nanostructured titanium dioxide (TiO 2) electrode with tetrasulfonated porphyrins (MTsPP; M=Zn, H 2) is reported. Cosensitization greatly enhances the photocurrent response at the Q band of H 2TsPP, with tenfold improvement of the quantum efficiency at 690 nm, and markedly decreases the photocurrent response in the Soret band of ZnTsPP with six-fold drop of the quantum efficiency at 430 nm. The maximum of the quantum efficiency at 690 nm reaches 14.5% on monochromatic illumination at 16.0 µW cm -2 when the TiO 2 electrode is cosensitized with H 2TsPP (0.40) and ZnTsPP (0.60). The photoelectric behavior of the cosensitized TiO 2 electrode is attributed to the formation of heteroaggregates between H 2TsPP and ZnTsPP molecules during the cosensitization of the TiO 2 electrode, resulting in a decrease of the surface concentration of H 2TsPP dimers and the presence of a low-lying charge-transfer state.