Near-IR light-sensitized voltaic conversion system using nanocrystalline TiO2 film by Zn chlorophyll derivative aggregated

A Zn chlorophyll-a derivative, Zn chlorin-e(6) (ZnChl-e(6)), adsorbed onto a nanocrystalline TiO2 film (ZnChl-e(6)/TiO2) electrode was prepared, and the photovoltaic properties of the ZnChl-e(6),/TiO2 electrode were studied. The absorption peaks of ZnChl-e(6)/TiO2 observed at 420, 654, and 795 nm were attributed to the ZnChl-e(6) molecules aggregating onto TiO2 film. The fluorescence attributed to the ZnChl-e(6) monomer and aggregate was observed at 710 and 820 nm, respectively, and the fluorescence in both cases was quenched by TiO2 particles. The maximum of the incident photon-to-current conversion efficiency (IPCE) value in the photocurrent action spectrum was 800 nm, and the IPCE value was 7.0%. ZnChl-e(6) molecules formed aggregates on a nanocrystalline TiO2 film electrode. From the photocurrent-photovoltage characteristics of the ZnChl-e(6)/TiO2 electrode irradiated with 100 mW cm(-2), the short-circuit photocurrent (I-SC) was found to be 0.19 mA cm(-2) and the open-circuit photovoltage (V-OC) was found to be 375 mV. The maximum power was estimated to be 28.7 mu W cm-2, and the fill factor (FF) was estimated to be 40.1%. A near-IR light induced photovoltaic conversion system using a ZnChl-e(6) aggregate formed onto a nanocrystalline TiO2 film electrode was achieved.