Apparatus for generating electricity using solar power and method for manufacturing same

A solar cell apparatus comprising:

• a substrate;
• a back electrode layer on the substrate;
• a light absorbing layer on the back electrode layer;
• a buffer layer on the light absorbing layer;
• a window layer on the buffer layer;
• and
• a connection part extending from the window layer and connected to the back electrode layer;
• wherein the window layer includes a first window layer and a second window layer;
• wherein an oxygen level of the window layer is gradually increased away from an interfacial surface between the light absorbing layer and the window layer;
• wherein the first window layer includes a first oxide on the light absorbing layer;
• wherein the second window layer is disposed on the first window layer;
• wherein the second window layer includes a second oxide having a composition ratio of oxygen higher than a composition ratio of oxygen contained in the first oxide;
• wherein the first window layer makes direct physical contact with the buffer layer;
• wherein the second window layer makes direct physical contact with the first window layer;
• wherein the connection part comprises:
• a first conductive layer integrally formed with the first window layer and directly making contact with the back electrode layer;
• and
• a second conductive layer integrally formed with the second window layer and provided on the first conductive layer;
• wherein the first conductive layer has a thickness smaller than a thickness of the second conductive layer,
• wherein the conductive layer has an oxygen composition ratio lower than an oxygen composition ratio of the second conductive layer;
• wherein the second window layer comprises a first upper surface and a second upper surface lower than the first upper surface, and
• wherein the second upper surface of the second window layer is lower than an upper surface of the light absorbing layer.