NOVELTY - A thin film solar cell, comprises: a substrate (21); a first electrode (22) disposed on the substrate; a barrier layer (23) disposed on the first electrode, where the material of the barrier layer is a conductive material; an ohmic contacting layer (24a) disposed on the barrier layer; an absorption layer (25a) disposed on the ohmic contacting layer; a buffer layer (26) disposed on the absorption layer; a transparent conductive layer (27) disposed on the buffer layer; and a second electrode (28) disposed on the transparent conductive layer.    USE - As thin film solar cell (claimed) such as silicon-based solar cells, dye-sensitized solar cells, and organic cells.    ADVANTAGE - The thin film solar cell not only favor the growth of the absorption layer but also control the thickness of the self-formed MoSe2 layer. Thus, it prevents the increase of the series resistance and the peeling of the absorption layer and forms high quality absorption layer with a smooth surface, which in turn reduces the leakage current and the carrier recombination probability, and thus increases the carrier collection and the photoelectron conversion efficiency. Thus provides a thin film solar cell with improved conversion efficiency.    DETAILED DESCRIPTION - A thin film solar cell, comprises: a substrate (21); a first electrode (22) disposed on the substrate; a barrier layer (23) disposed on the first electrode, where the material of the barrier layer is a conductive material; an ohmic contacting layer (24a) disposed on the barrier layer; an absorption layer (25a) disposed on the ohmic contacting layer; a buffer layer (26) disposed on the absorption layer; a transparent conductive layer (27) disposed on the buffer layer; and a second electrode (28) disposed on the transparent conductive layer. The substrate is a glass substrate, metal substrate, or a plastic substrate. The ohmic contacting layer is a molybdenum selenide (MoSe2) layer. The first electrode is a molybdenum (Mo) electrode. An INDEPENDENT CLAIM is included for a method for manufacturing the thin film solar cell, involving: providing a substrate; forming a first electrode on the substrate; forming a barrier layer on the first electrode, where the material of the barrier layer is a conductive material; forming a Mo-containing layer on the barrier layer; forming an absorption-layer precursor on the Mo-containing layer, and performing a selenization process or a sulfation process to transfer the absorption-layer precursor and the Mo-containing layer into an absorption layer and an ohmic contacting layer respectively; forming a buffer layer on the absorption layer; forming a transparent conductive layer on the buffer layer; and forming a second electrode on the transparent conductive layer.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a process for manufacturing the thin film solar cell.    Substrate (21)    First electrode (22)    Barrier layer (23)    Ohmic contacting layer (24a)    Absorption layer (25a)    Buffer layer (26)    Transparent conductive layer (27)    Second electrode (28)