NOVELTY - The thin film solar cell (200) comprises a substrate (210), a first conductive layer (220) disposed on the substrate, a first photovoltaic layer (230) disposed on the first conductive layer, a second conductive layer (250) disposed on the first photovoltaic layer, a crystallization layer partially disposed between the first photovoltaic layer and the first conductive layer or between the first photovoltaic layer and the second conductive layer, and a second photovoltaic layer (240) disposed between the first photovoltaic layer and the second conductive layer.    USE - Used as a thin film solar cell.    ADVANTAGE - The thin film solar cell can be economically manufactured with high yield and improved electrical performance, and reduces the inter-diffusion effect between the photovoltaic layers and the dangling bonds on the contact surface between film layers thus improving the photoelectric conversion efficiency.    DETAILED DESCRIPTION - The thin film solar cell (200) comprises a substrate (210), a first conductive layer (220) disposed on the substrate, a first photovoltaic layer (230) disposed on the first conductive layer, a second conductive layer (250) disposed on the first photovoltaic layer, a crystallization layer partially disposed between the first photovoltaic layer and the first conductive layer or between the first photovoltaic layer and the second conductive layer, and a second photovoltaic layer (240) disposed between the first photovoltaic layer and the second conductive layer, where the crystallization layer is partially disposed between second photovoltaic layer and the second conductive layer and/or partially disposed between the first photovoltaic layer and the second photovoltaic layer. A material of the crystallization layer comprises a semiconductor, a metal or a metal oxide. Each of the first photovoltaic layer and the second photovoltaic layer is a group IV thin film, III-V compound semiconductor thin film, II-VI compound semiconductor thin film, and/or organic compound semiconductor thin film. One of the first conductive layer and the second conductive layer is a transparent conductive layer. The thin film solar cell includes an interlayer disposed between the first photovoltaic layer and the second photovoltaic layer so as to reduce an inter-diffusion effect generated between the first photovoltaic layer and the second photovoltaic layer, and a second electrode layer disposed on the second photovoltaic layer. A material of the interlayer is an intrinsic semiconductor or a metal oxide semiconductor. Each of the first photovoltaic layer and the second photovoltaic layer is a PN semiconductor layer or a PIN semiconductor layer. An INDEPENDENT CLAIM is included for a manufacturing method of a thin film solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows a local cross-sectional view of a thin film solar cell.    Thin film solar cell (200)    Substrate (210)    First conductive layer (220)    First photovoltaic layer (230)    Second photovoltaic layer (240)    Second conductive layer. (250)