A solar cell (10, 40, 50), comprising: a semiconductor base having a first surface and a second surface, wherein the semiconductor base has a first doped type; and a first doped semiconductor layer disposed on the first surface of the semiconductor base, the first doped semiconductor layer comprising at least one doped contact region, both of the first doped semiconductor layer and the at least one doped contact region having a second doped type contrary to the first doped type, and a dopant concentration of the at least one doped contact region being substantially higher than a dopant concentration of the first doped semiconductor layer; an insulating layer disposed on the first doped semiconductor layer, the insulating layer having at least one opening exposing the at least one doped contact region; a second doped semiconductor layer disposed on the insulating layer and the at least one doped contact region, the second doped semiconductor layer having the second doped type, the dopant concentration of the at least one doped contact region being substantially higher than a dopant concentration of the second doped semiconductor layer, the dopant concentration of the second doped semiconductor layer being substantially higher than the dopant concentration of the first doped semiconductor layer, and the dopant concentration of the second doped semiconductor layer being substantially between the dopant concentration of the at least one doped contact region and the dopant concentration of the first doped semiconductor layer, wherein the second doped semiconductor layer is fully covering on the insulating layer and on the at least one doped contact region of the first doped semiconductor layer exposed by the at least one opening of the insulating layer; and a first electrode layer disposed on the second doped semiconductor layer, the first electrode layer being corresponding to the at least one doped contact region. a semiconductor base having a first surface and a second surface, wherein the semiconductor base has a first doped type; and a first doped semiconductor layer disposed on the first surface of the semiconductor base, the first doped semiconductor layer comprising at least one doped contact region, both of the first doped semiconductor layer and the at least one doped contact region having a second doped type contrary to the first doped type, and a dopant concentration of the at least one doped contact region being substantially higher than a dopant concentration of the first doped semiconductor layer; an insulating layer disposed on the first doped semiconductor layer, the insulating layer having at least one opening exposing the at least one doped contact region; a second doped semiconductor layer disposed on the insulating layer and the at least one doped contact region, the second doped semiconductor layer having the second doped type, the dopant concentration of the at least one doped contact region being substantially higher than a dopant concentration of the second doped semiconductor layer, the dopant concentration of the second doped semiconductor layer being substantially higher than the dopant concentration of the first doped semiconductor layer, and the dopant concentration of the second doped semiconductor layer being substantially between the dopant concentration of the at least one doped contact region and the dopant concentration of the first doped semiconductor layer, wherein the second doped semiconductor layer is fully covering on the insulating layer and on the at least one doped contact region of the first doped semiconductor layer exposed by the at least one opening of the insulating layer; and a first electrode layer disposed on the second doped semiconductor layer, the first electrode layer being corresponding to the at least one doped contact region.