Photovoltaic conversion system using carotenoid-chlorophyll assembled TiO2 film electrode

Zn chlorophyll-a derivative, Zn chlorin-e6 (ZnChl-e6) and carotenoid derivative, crocetin (Cro) adsorbed onto a nanocrystalline TiO2 film (ZnChl-e6-Cro/TiO2) electrode was prepared and the photovoltaic properties of ZnChl-e6-Cro/TiO2 electrode were studied. Incident photon to current efficiency (IPCE) value at 640 nm in photocurrent action spectrum of ZnChl-e6-Cro/TiO2 electrode was ca. 2.50%. In contrast, IPCE value at 640 nm in ZnChl-e6/TiO2 electrode was ca. 1.27%. Thus, the IPCE value increases by co-adsorbed crocetin and ZnChl-e6 onto TiO2 film electrode. From the results of photocurrent responses with light intensity of 100 mW cm−2 irradiation, generated photocurrents in the ZnChl-e6-Cro/TiO2 and ZnChl-e6/TiO2 electrodes are 380 and 180 μA cm−2, respectively. Photocurrent increases using ZnChl-e6-Cro/TiO2 electrode compared with that of ZnChl-e6/TiO2 electrode.