MOSE2 ELECTROCHEMICAL SOLAR-CELL - ANODIC COUPLING OF ELECTRON-TRANSFER TO D-]D PHOTO-TRANSITIONS IN LAYER CRYSTALS

N - TYPE MoSe//2 layer crystals were successfully used as photoelectrodes in electrochemical solar cells. Their mechanism is based on d yields d phototransitions in the electrode in combination with anodic electron transfer from suitable redox couples in the adjoining electrolyte (fe**2** plus **3** plus . O** minus /I//2). Redox agents with potentials more negative than that of water can be oxidized by holes from the low lying Mo 4d//z2 energy band clearly before the anodic onset of the photoreaction with water molecules which would lead to the formation of selenic acid and to a gradual photodissolution of the electrode. In this way it is possible to operate regenerative electrochemical solar cells bypassing corrosive anodic reactions. With MoSe//2:I** minus /I//2 solar cells photocurrent densities of 22 mA/cm**2, photovoltages of 0. 55 V and energy conversion efficiencies between 4 and 5% were obtained in the red and near infrared spectral region.