Patent ID: 9640685
Date: 2017-05-02
CPC Classifications: H01L,Y02E,Y02P

Claim:
1. A solar cell comprising: a back electrode layer; a light absorbing layer on the back electrode layer; and a buffer layer on the light absorbing layer; wherein the buffer layer includes a first buffer layer, a second buffer layer on the first buffer layer, and a third buffer layer on the second buffer layer; wherein energy bandgaps sequentially decrease from the third buffer layer to the second buffer layer, wherein energy bandgap of the second buffer layer is about 1.7 eV; wherein energy bandgap of the third buffer layer is about 2.4 eV; wherein a thickness of the first buffer layer is smaller than a thickness of the second buffer layer, and the thickness of the second buffer layer is smaller than a thickness of the third buffer layer; wherein the thickness of the first buffer layer is less than 10 nm, wherein the thickness of the second buffer layer is in a range of 10 nm to 20 nm, wherein the thickness of the third buffer layer is in a range of 30 nm to 40 nm, wherein the first buffer layer includes a group I-VI compound.