Solar cell and method of fabricating the same

A solar cell comprising:

• a support substrate;
• a back electrode layer on the support substrate;
• a light absorbing layer on the back electrode layer;
• a buffer layer on the light absorbing layer;
• a high resistance buffer layer comprising ZnO, without impurities, and disposed on the buffer layer;
• and
• a front electrode layer on the high resistance buffer,
• wherein the light absorbing includes a Cu(Ga,In)Se2 (CIGS) crystal structure,
• wherein the front electrode layer has a thickness in a range of from 500 nm to 1.5 μm,
• wherein the front electrode layer is doped with 1.5 wt % to 3.5 wt % aluminum (Al),
• wherein the buffer layer comprises magnesium zinc oxide (MgZnO) and a mass ratio of the Mg to Zn in the magnesium zinc oxide is less than or equal to 0.7,
• wherein the light absorbing layer includes an undoped region and a doping region on the undoped region,
• wherein the undoped region is disposed on and in direct contact with the back electrode layer,
• wherein the doping region is disposed on the undoped region,
• wherein the doping region is in direct contact with the buffer layer,
• wherein a thickness of the undoped region is less than 50% of a thickness of the doping region,
• wherein the doping region comprises zinc,
• wherein an amount of the zinc in the doping region is in a range of 0.1 wt % to 3 wt %;
• and
• wherein the doping region of the light absorbing layer forms a homogenous PN junction together with the undoped region of the light absorbing layer, and wherein the doping region has an energy bandgap similar to that of the undoped region.