Solar cell apparatus and method of fabricating the same

A solar cell apparatus comprising:

• a substrate;
• a back electrode layer on the substrate;
• a light absorbing layer on the back electrode layer;
• and
• a front electrode layer on the light absorbing layer,
• wherein the light absorbing layer comprises:
• a first region having a conduction band which is gradually increased in a direction of the front electrode;
• a second region on the first region, the second region having a conduction band which is gradually decreased in a direction of the front electrode;
• a third region on the second region, the third region having a conduction band which is gradually increased in a direction of the front electrode;
• and
• a fourth region on the third region, the fourth region having a conduction band which is gradually decreased in a direction of the front electrode.

A method of fabricating a solar cell apparatus, the method comprising:

• forming a back electrode layer on a substrate;
• forming a light absorbing layer on the back electrode layer;
• and
• forming a front electrode layer on the light absorbing layer,
• wherein the light absorbing layer comprises:
• a first region having a bandgap energy which is gradually increased in a direction of the front electrode;
• a second region on the first region, the second region having a bandgap energy which is gradually decreased in a direction of the front electrode layer;
• a third region on the second region, the third region having a bandgap energy which is gradually increased in a direction of the front electrode layer;
• and
• a fourth region on the first region, the fourth region having a bandgap energy which is gradually decreased in a direction of the front electrode layer.