A multi-junction solar cell structure includes a supporting substrate, a Group IV element-based thin film, and a Group III-V element-based thin film sequentially stacked on the supporting substrate. When the multi-junction solar cell structure is active, the Group III-V element-based thin film contacts the light before the Group IV element-based thin film does. The Group IV element-based thin film includes a first solar cell and the Group III-V element-based thin film includes a second solar cell, wherein the band gap of the first solar cell is lower than the band gap of the second solar cell.