NOVELTY - The cell has a light absorption layer (400) placed on an electrode (300), which is provided with silicon containing oxygen. Another light absorption layer (600) is placed on the former layer, which is provided with silicon containing germanium. Another electrode (700) is placed on the latter layer. The former layer includes a set of semiconductor layers provided with oxygen-content ratios different from each other. The latter absorption layer includes a set of semiconductor layers provided with germanium-content ratios different from each other.    USE - Thin film silicon solar cell e.g. crystalline silicon solar cell and thin film solar cell such as amorphous/crystalline silicon thin film solar cell, copper-indium-gallium-selenium (CIGS) thin film solar cell, cadmium-tellurium thin film solar cell and dye-sensitized solar cell, for use as a photoelectric conversion system for converting light energy output from sun into electric energy/power during generation of electric power.    ADVANTAGE - The cell increases light absorption rate by suitably controlling energy band gaps of light absorption layers of a tandem structure and by effectively scattering sunlight using a selective transmitting layer. The cell reduces an energy band gap of amorphous silicon if content of germanium increases. The selective transmitting layer between the light absorption layers can reflect visible light and selectively transmit infrared rays, so that the sunlight can be effectively scattered to improve light absorption efficiency of the cell and interface defects of the cell can be reduced. The cell is highlighted as an environment-friendly energy source. The selective transmitting layer scatters light to reduce light loss.    DETAILED DESCRIPTION - The cell is made of includes aluminum-titanium oxide, silicon-titanium oxide, aluminum-zirconium oxide, zirconium-titanium oxide, hafnium-titanium oxide, zirconium oxide, titanium oxide, hafnium oxide, aluminum oxide, silicon oxide and silicon oxynitride. The cell includes an inorganic substrate formed of quartz and glass and a transparent plastic substrate formed of polyethylene terephthalate (PET), polyethylene naphathalate (PEN), polycarbonate, polystyrene and polypropylene.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a thin film solar cell including a tandem structure.    Substrate (100)    Reflection preventing layer (200)    Electrodes (300, 700)    Light absorption layers (400, 600)    Selective transmitting layer (500)