(JP6507999-W)      A regenerable photo-electrochemical cell (1) has a 1st transparent substrate (2) with a 1st transparent electrode (6) and a 2nd transparent substrate (4) with a 2nd transparent electrode (8) coated with a 1st photo-electrochemically active oxide semiconductor layer (10) in the form of a porous nano-structure of sintered colloidal particles the substrates (2,4) being arranged to define a space filled with electrolyte (16) which impregnates the porous structure so that it is in contact with both the 1st electrode (6) and the 2nd electrode (8). The 2nd substrate (4) also has a continuous, dense 2nd layer (20) of oxide semiconductor extending between the second electrode (8) and the 1st oxide semiconductor layer (10), this 2nd layer (20) pref. having the same nature as the 1st layer (10).    ADVANTAGE -   The cell exhibits no incident light diffusion, little or no absorption of visible radiation and satisfactory energy conversion yield of incident light into electrical energy, the 2nd layer increasing yield and stability with time without the need for chromophore addn..    (US5441827-A)      A regenerating photoelectrochemical cell comprises 1st and 2nd transparent substrates with respective electrodes, the 2nd electrode deposited with a layer of a photoelectrochemically active semiconductor oxide in the form of a porous nanostructure of sintered colloidal particles 10-20000nm thick. The substrates face each other through an electrolyte which is in contact with both electrodes and which impregnates the porous structure. The 2nd substrate also has a compact, continuous 2nd semiconductor oxide layer 10-50 nm thick extending between the 2nd electrode and 1st semiconductor oxide layer and made of the same material. The electrolyte is polyoxyethylene/LiI or LiI and pyridinium iodide.    ADVANTAGE -   The cell does not diffuse incident light and does not absorb light in the visible range. Satisfactory conversion rate of incident light energy to electrical energy.