NOVELTY - The thin film solar cell (100) comprises a substrate (110), a first conductive layer (120) disposed on the substrate, a photovoltaic layer (130) disposed on the first conductive layer, an interlayer (140) disposed between the first conductive layer and the photovoltaic layer, a second conductive layer (150) disposed on the photovoltaic layer, and a protection layer disposed on the photovoltaic layer, opposite to the first conductive layer and between the photovoltaic layer and the second conductive layer. The electron-hole pairs generated as the photovoltaic layer is illuminated.    USE - Used as a thin film solar cell such as an amorphous silicon thin film solar cell, a microcrystalline silicon thin film solar cell, a tandem thin film solar cell, a triple thin film solar cell, a copper indium diselenide thin film solar cell, a copper indium gallium diselenide thin film solar cell, a cadmium telluride thin film solar cell or an organic thin film solar cell.    ADVANTAGE - The thin film solar cell can be economically, efficiently and simply manufactured with higher photoelectric conversion efficiency and electrical performance.    DETAILED DESCRIPTION - The thin film solar cell (100) comprises a substrate (110), a first conductive layer (120) disposed on the substrate, a photovoltaic layer (130) disposed on the first conductive layer, an interlayer (140) disposed between the first conductive layer and the photovoltaic layer, a second conductive layer (150) disposed on the photovoltaic layer, and a protection layer disposed on the photovoltaic layer, opposite to the first conductive layer and between the photovoltaic layer and the second conductive layer. The electron-hole pairs generated as the photovoltaic layer is illuminated. The interlayer reduces dangling bonds on a surface of the photovoltaic layer to prevent surface recombination of the electron-hole pairs from occurring on the surface of the photovoltaic layer. A thickness of the interlayer and the protection layer is more than 0 Angstrom and less than or equal to 1000 Angstrom . A material of the interlayer and the protection layer is a dielectric material, an insulating material or an oxygen-containing compound. The first conductive layer has first openings to expose a portion of the substrate, and the photovoltaic layer has second openings to expose a portion of the first conductive layer. The photovoltaic layer is: a Group IV thin film, a III-V compound semiconductor thin film, a II-VI compound semiconductor thin film or an organic compound semiconductor thin film; and physically connected to the substrate through the first openings. The second conductive layer has third openings to expose the portion of the first conductive layer and a portion of a side surface of the photovoltaic layer, and is physically connected to the first conductive layer through the second openings. The third openings and a portion of the second openings are disposed at the same positions. An INDEPENDENT CLAIM is included for a manufacturing method of a thin film solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows a cross-sectional view of a thin film solar cell.    Thin film solar cell (100)    Substrate (110)    First conductive layer (120)    Photovoltaic layer (130)    Interlayer (140)    Second conductive layer. (150)