Solar cell and method for manufacturing same

1. 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 front electrode layer on the buffer layer; and

a first through hole formed through the back electrode layer and the light absorbing layer,

wherein the buffer layer includes cadmium sulfide (CdS),

wherein a step difference is formed between the back electrode layer and the light absorbing layer,

wherein a side surface of the light absorbing layer protrudes with respect to a side surface of the back electrode layer in the first through hole,

wherein a portion of the buffer layer and a portion of the front electrode layer are disposed in the first through hole,

wherein the portion of the buffer layer directly makes contact with a top surface of the support substrate, both side surfaces of the back electrode layer, both side surfaces of the light absorbing layer, and a bottom surface of the light absorbing layer exposed through the first through hole;

wherein the portion of the buffer layer directly makes contact with an entire surface of the top surface of the support substrate exposed through the first through hole, and

wherein the portion of the front electrode layer directly makes contact with a side surface of the buffer layer and a top surface of the buffer layer disposed in the first through hole.

2. The solar cell of claim 1 , wherein the step difference between the back electrode layer and the light absorbing layer has a reverse stair shape.

3. The solar cell of claim 1 , wherein the step difference between the back electrode layer and the light absorbing layer is filled with the buffer layer.

4. The solar cell of claim 1 , wherein the buffer layer comprises:

a first buffer layer between the light absorbing layer and the front electrode layer; and

a second buffer layer between the back electrode layer and the front electrode layer.

5. The solar cell of claim 4 , wherein a width of the second buffer layer is larger than a width of the first buffer layer.

6. The solar cell of claim 1 , wherein, in the first through hole, a first distance (D 1 ) between the side surface of the back electrode layer and a side surface of the front electrode layer is longer than a second distance (D 2 ) between the side surface of the light absorbing layer and the side surface of the front electrode layer.

7. The solar cell of claim 6 , wherein a ratio (D 1 : D 2 ) between the first and second distances is in a range of about 2: 1 to about 200: 1.

8. 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 front electrode layer on the buffer layer; and

a first through hole formed through the back electrode layer and the light absorbing layer,

wherein the buffer layer includes cadmium sulfide (CdS),

wherein the light absorbing layer makes contact with top and side surfaces of the back electrode layer,

wherein a portion of the buffer layer and a portion of the front electrode layer are disposed in the first through hole,

wherein the portion of the buffer layer directly makes contact with a top surface of the support substrate, a side surface of the back electrode layer, and a side surface of the light absorbing layer exposed through the first through hole; and

wherein the portion of the front electrode layer directly makes contact with a side surface of the buffer layer and a top surface of the buffer layer disposed in the first through hole.

9. The solar cell of claim 8 , wherein the light absorbing layer has a reverse-L shape.

10. The solar cell of claim 1 ,

wherein the buffer layer is disposed while filling the step difference between the back electrode layer and the light absorbing layer.

11. The solar cell of claim 8 , wherein the buffer layer comprises:

a first buffer layer between the light absorbing layer and the front electrode layer; and

a second buffer layer between the back electrode layer and the front electrode layer.

12. The solar cell of claim 11 , wherein a width of the second buffer layer is larger than a width of the first buffer layer.

13. The solar cell of claim 1 , further comprising a second through hole formed through the light absorbing layer and the buffer layer and spaced apart from the first through hole,

wherein a connection part extending downward from the front electrode layer is disposed in the second through hole.

14. The solar cell of claim 8 , further comprising a second through hole formed through the light absorbing layer and the buffer layer and spaced apart from the first through hole,

wherein a connection part extending downward from the front electrode layer is disposed in the second through hole.