(AT510156-A4)   NOVELTY - Photoelectrochemical cell (1) for solar driven decomposition of a starting material, preferably water or carbon dioxide, into a product gas bonded to the starting material, preferably hydrogen or carbon monoxide, comprises: a supply line for the starting material; a discharge line for the obtained product gas; a first electrode (2) made of a photoelectrically active material, exposed to solar radiation during operation; a second electrode (5); and an ion conductor (6) for transporting ions produced during the decomposition of the starting material, comprising electrolyte.    USE - The photoelectrochemical cell is useful for solar driven decomposition of a starting material, preferably water or carbon dioxide, into a product gas bonded to the starting material, preferably hydrogen or carbon monoxide.    ADVANTAGE - The photoelectrochemical cell: exhibits thermal stability in a wide range of temperature; and makes use of an ion conductor exhibiting improved ion-conducting properties.    DETAILED DESCRIPTION - Photoelectrochemical cell (1) for solar driven decomposition of a starting material, preferably water or carbon dioxide, into a product gas bonded to the starting material, preferably hydrogen or carbon monoxide, comprises: a supply line for the starting material; a discharge line for the obtained product gas; a first electrode (2) made of a photoelectrically active material, exposed to solar radiation during operation; a second electrode (5); and an ion conductor (6) for transporting ions produced during the decomposition of the starting material, comprising an electrolyte made of a heat resistant solid material, arranged between the electrodes. The electrodes are connected with each other in a closed circuit through an electron conductor (4) for transporting electrons that are excited by the solar radiation in the first electrode. An INDEPENDENT CLAIM is also included for solar driven decomposition of a starting material, preferably water or carbon dioxide, to a product gas bonded to the starting material, preferably hydrogen or carbon monoxide, comprising exciting charge carriers in the form of electron-hole pairs by solar radiation in a photoelectrically active first electrode, passing the excited electrons to a second electrode, adding the starting material to one of the electrodes, in which the starting material is decomposed through the excited charge carriers to generate ions, transporting the generated ions in a closed circuit to respectively further electrode, and discharging the obtained product gas, where the ion transport between the electrodes takes place through an electrolyte comprising a solid material, preferably a solid material oxide.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the photoelectrochemical cell, which is formed as a panel.    Photoelectrochemical cell (1)    Photoelectrically active first electrode (2)    Electron conductor (4)    Second electrode (5)    Ion conductor (6)