(WO9414199-A1)      The tandem photovoltaic device comprises a stacked array of photovoltaic cells disposed in an optical and electrical series relationship. The array comprises a first cell disposed on a substrate, the cell comprising a layer of intrinsic semiconductor material interposed between a first layer of P-doped semiconductor material and a first layer of N-doped semiconductor material, and being operative, when it is incorporated in the tandem photovoltaic device and the device is subjected to illumination, to generate a first photocurrent in response to the absorption of light. A second photovoltaic cell is superposed onto the first photovoltaic cell, the second cell comprising a second layer of intrinsic semiconductor material of a preselected thickness interposed between a second layer of P-doped semiconductor material and a second layer of N-doped semiconductor material.    The thickness of the second layer of intrinsic semiconductor material is selected so that the second photocurrent is less than the first. The first layer of intrinsic semiconductor material is prepared by a first deposition process and the second layer by a second deposition process. The material quality of the second material is greater than the material quality of the first layer.    USE/ADVANTAGE -   E.g. for power generation. Improved photo-conversion efficiency.    (JP8504542-W)      The tandem photovoltaic device comprises a stacked array of photovoltaic cells disposed in an optical and electrical series relationship. The array comprises a first cell disposed on a substrate, the cell comprising a layer of intrinsic semiconductor material interposed between a first layer of P-doped semiconductor material and a first layer of N-doped semiconductor material, and being operative, when it is incorporated in the tandem photovoltaic device and the device is subjected to illumination, to generate a first photocurrent in response to the absorption of light. A second photovoltaic cell is superposed onto the first photovoltaic cell, the second cell comprising a second layer of intrinsic semiconductor material of a preselected thickness interposed between a second layer of P-doped semiconductor material and a second layer of N-doped semiconductor material.    The thickness of the second layer of intrinsic semiconductor material is selected so that the second photocurrent is less than the first. The first layer of intrinsic semiconductor material is prepared by a first deposition process and the second layer by a second deposition process. The material quality of the second material is greater than the material quality of the first layer.    USE/ADVANTAGE -   E.g. for power generation. Improved photo-conversion efficiency.