Copper zinc tin germanium selenium thin film, preparation method thereof and copper zinc tin germanium selenium thin film solar cell

The invention relates to a copper zinc tin germanium selenium thin film, which comprises an incident light layer, a middle layer and a back light layer which are sequentially stacked. The incident light layer comprises a first incident light surface and a first back light surface opposite to the first incident light surface. Molar ratio of germanium and tin in the material of the incident light layer is gradually decreased along a direction from the first incident light surface to the first back light surface. Molar ratio of germanium and tin in the material of the middle layer is equal to molar ratio of germanium and tin in the material of the first back light surface. The back light layer comprises a second incident light surface which is connected with the middle layer and a second back light surface which is far away from the middle layer. The first back light surface is connected with the second incident light surface through the middle layer. Molar ratio of germanium and tin in the material of the back light layer is gradually increased along a direction from the second incident light surface and the second back light surface. The invention additionally provides a preparation method of the copper zinc tin germanium selenium thin film and a solar cell using the copper zinc tin germanium selenium thin film.