Solar energy conversion by organic photoelectrochemical cells has been intensively investigated. Dye-sensitized cells such as Grätzel cell which is made from titanium dioxide coated with ruthenium complex seem to be promising as solar cell in a level of practical application. Organic-based photovoltaic cells, which mimic photoinduced multistep electron transfer processes in photosynthesis, have been developed in recent years. Sequential electron relay in primary processes of photosynthesis has been realized in multi-arrays of pigments connected with covalent bonds as photosynthetic model. A variety of techniques, such as Langmuir-Blodgett (LB) films, lipid bilayer membranes, and self-assembled monolayers, have been applied for construction of photovoltaic device where pigments including donor, sensitizer, and acceptor, are arranged unidirectionally at the molecular level on electrode surfaces. In the light of the rapid progress in these fields organic-based solar cells will be much improved in the near future.