NOVELTY - A photoelectrochemical cell (100) comprises a 1st electrode (120) having a conductor (121), a titanium oxide layer positioned on the conductor, and a chromophore layer (124) formed of chromophore adsorbed to the surface of the titanium oxide layer, a 2nd electrode (130) electrically connected to the conductor, an electrolyte which is involved in charge transport during charging/discharging process and in contact with the surface of a chromophore layer side of the 1st electrode and the surface of the 2nd electrode, and a container (110).    USE - A photoelectrochemical cell for energy system (claimed).    ADVANTAGE - Electric power is efficiently produced.    DETAILED DESCRIPTION - A photoelectrochemical cell (100) comprises a 1st electrode (120) having a conductor (121), a titanium oxide layer positioned on the conductor, and a chromophore layer (124) formed of chromophore adsorbed to the surface of the titanium oxide layer, a 2nd electrode (130) electrically connected to the conductor, an electrolyte which is involved in charge transport during charging/discharging process and in contact with the surface of a chromophore layer side of the 1st electrode and the surface of the 2nd electrode, and a container (110) which accommodates the 1st electrode, the 2nd electrode, and the electrolyte. The titanium oxide layer has different crystal structures in a region near the chromophore layer and a region near the conductor. In the region near the chromophore layer, abundance ratio of anatase-type titanium oxide is higher than the abundance ratio of rutile-type titanium dioxide. In the region near the conductor, abundance ratio of rutile-type titanium dioxide is higher than the abundance-ratio of anatase-type titanium oxide. Fermi level in the region near the conductor of the titanium oxide layer is larger than the Fermi level in the region near the chromophore layer of the titanium oxide layer. Fermi level in the conductor is larger than the Fermi level in the region near the conductor of the titanium oxide layer. Electricity is generated by irradiating light to the chromophore layer of the 1st electrode. An INDEPENDENT CLAIM is included for an energy system using the photoelectrochemical cell.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the photoelectrochemical cell.    Photoelectrochemical cell (100)    Container (110)    1st electrode (120)    Conductor (121)    Chromophore layer (124)