Patent ID: 8581092

Claim:
A tandem solar cell comprising: a substrate; a front electrode disposed on the substrate; a back electrode disposed opposite to the front electrode on the substrate; a first cell disposed below the front electrode and including a first buffer layer and a first light absorption layer; and a second cell disposed above the back electrode and including a second light absorption layer and a second buffer layer, wherein the first light absorption layer consists of a CuGaSeS layer and a CuGaSe layer, the second light absorption layer includes a semiconductor compound selected from the group consisting of CuInSe 2 , CuInGaSe 2 , CuInSeS, CuInGaSeS and a combination thereof, and the CuGaSeS layer of the first light absorption layer is disposed closer than the CuGaSe layer of the first light absorption layer to the front electrode.