In this presentation, we will introduce an artificial photosynthesis system for the solar fuel production from the water. Among the various artificial photosynthesis systems, we are focusing the dye-sensitized photoelectrochemical cell (DSPEC), which is molecular level light absorption and oxidation (or reduction) catalyst approaches. In the DSPEC, the achievement of long-lived photoinduced redox separation lifetimes has long been a central goal of molecular-based solar energy conversion strategies. The longer the redox-separation lifetime, the more time available for useful work to be extracted from the absorbed photon energy. Here we describe a novel strategy for dye-sensitized solar energy applications in which redox-separated lifetimes on the order of milliseconds to seconds can be achieved based on a simple toolkit of molecular components. Specifically, molecular chromophores (C), electron acceptors (A) and electron donors (D) were self-assembled on the surfaces of mesoporous, transparent conducting indium tin oxide nanoparticle (nanoITO) electrodes to prepare both photoanode (nanoITO|?밃?밅?밆) and photocathode (nanoITO|?밆?밅?밃) assemblies. Nanosecond transientabsorption and steady-state photolysis measurements show that the electrodes function microscopically as molecular analogues of semiconductor p/n junctions. These results point to a new chemical strategy for dye-sensitized solar energy conversion based on molecular excited states and electron acceptors/donors on the surfaces of transparent conducting oxide nanoparticle electrodes.