Chlorophyll assembled electrode for photovoltaic conversion device

Chlorophyll-a (Chl-a) assembled in hydrophobic domain by fatty acid with long alkyl hydrocarbon chain such as myristic acid (Myr), stearic acid (Ste) and cholic acid (Cho) modified onto nanocrystalline TiO₂ electrode is prepared and the photovoltaic properties of the nanocrystalline TiO₂ film by Chl-a are studied. Incident photon to current efficiency (IPCE) value at 660 nm in photocurrent action spectrum of Chl-a/Ste-TiO₂, Chl-a/Myr-TiO₂ and Chl-a/Cho-TiO₂ electrodes are 5.0%, 4.1% and 4.1%, respectively. Thus, the IPCE is maximum using Chl-a/Ste-TiO₂ electrode. From the results of photocurrent responses with light intensity of 100 mW cm⁻² irradiation or monochromatic light with 660 nm, generated photocurrent increases using Chl-a/Ste-TiO₂ electrode compared with the other Chl-a assembled TiO₂ electrodes. These results show that the hydrophobic domain formed by stearic acid with long alkyl hydrocarbon chain is suitable for fixation of Chl-a onto TiO₂ film electrodes and photovoltaic performance is improved using Chl-a onto Ste-TiO₂ film electrode.