NOVELTY - The thin-film solar cell comprises a substrate (210), a first conductive layer (220) disposed on the substrate, photovoltaic layers (232, 234) that are stacked on the first conductive layer and are present in electrical tandem with each other, a second conductive layer (240) disposed on the photovoltaic layers, a first passivation layer (252) disposed on the second conductive layer, and a second passivation layer (254) disposed on the first passivation layer. The photovoltaic layers: are adapted to generate a photocurrent; and have an opening exposing the first conductive layer.    USE - Used as a thin-film solar cell such as copper indium gallium selenium thin film solar cell and cadmium telluride thin-film solar cell.    ADVANTAGE - The thin-film solar cell can be economically and simply manufactured with improved photoelectric conversion efficiency and excellent performance.    DETAILED DESCRIPTION - The thin-film solar cell comprises a substrate (210), a first conductive layer (220) disposed on the substrate, photovoltaic layers (232, 234) that are stacked on the first conductive layer and are present in electrical tandem with each other, a second conductive layer (240) disposed on the photovoltaic layers, a first passivation layer (252) disposed on the second conductive layer, and a second passivation layer (254) disposed on the first passivation layer. The photovoltaic layers: are adapted to generate a photocurrent; have an opening exposing the first conductive layer; include a stack structure of a tandem junction design, a triple junction design or having more than three junctions; and are made of a group IV element semiconductor thin film, a group III-V compound semiconductor thin film, a group II-VI compound semiconductor thin film and/or an organic compound semiconductor thin film. The group IV element semiconductor thin film comprises carbon element thin film, silicon element thin film, germanium elemental thin film, silicon carbide thin film and/or germanium silicide thin film in a monocrystalline phase, a polycrystalline phase, an amorphous phase or a microcrystalline phase. The group III-V compound semiconductor thin film comprises a gallium arsenide compound thin film and/or an indium gallium phosphide compound thin film. The group II-VI compound semiconductor thin film comprises a copper indium selenium compound thin film, copper indium gallium selenium compound thin film and/or cadmium telluride compound thin film. The organic compound semiconductor thin film comprises a mixture of a conjugated polymer donor and a carbon nanosphere acceptor. The second conductive layer is electrically connected with the first conductive layer of an adjacent one of sub-cells through the opening. The first and second passivation layers are used to reflect a light ray within a wavelength range of 300-1100 nm from an UV band to an infrared band into the photovoltaic layers so as to make the photocurrents generated by the photovoltaic layers matched with each other, and are made of a dielectric material, an insulation material, and/or a compound comprising oxygen and/or nitrogen element. The first passivation layer has a refractive index different from that of the second passivation layer, and a thickness identical or different from that of the second passivation layer, and is made of a light transmissive material. The second passivation layer is made of a reflective material. The first and second conductive layers are made of a transparent conductive layer. An INDEPENDENT CLAIM is included for a method for manufacturing a thin-film solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a thin-film solar cell.    Substrate (210)    First conductive layer (220)    Photovoltaic layers (232, 234)    Second conductive layer (240)    First passivation layer (252)    Second passivation layer. (254)