Thin film solar cell with finger pattern
View Patent ↗The present invention relates to thin film solar cell structures and methods of manufacturing them. In particular and in one aspect the present invention is related to apparatus and methods for forming a solar cell structure in which an insulator film is disposed over a region of a conductive contact layer, which is either adjacent or below the absorber layer.
1. A solar cell structure comprising:
a substrate with a top surface, an edge, a sidewall and a bottom surface;
a conductive contact layer with a top surface disposed on the top surface of the substrate,
an insulator film directly disposed on a region of the top surface of the conductive contact layer;
an absorber layer disposed on at least another region of the conductive contact layer that is different from the region on which the insulator film is disposed, and wherein the absorber layer is not disposed on the region of the conductive contact layer where the insulator film is disposed;
a transparent conductive layer disposed on at least the absorber layer; and
a finger pattern including a set of fingers and a busbar, the finger pattern being disposed on the transparent conductive layer, wherein the busbar is aligned substantially over the insulator film so that the busbar is not disposed over the at least another region where the absorber layer is disposed on the conductive contact layer.
2. The solar cell structure according to claim 1 wherein the absorber layer is disposed on both the conductive contact layer and the insulator film such that a portion of the absorber layer is disposed over the conductive contact layer and another portion of the absorber layer is disposed over the insulator film, and wherein the transparent conductive layer is disposed over the absorber layer.
3. The structure according to claim 2 wherein the substrate is conductive.
4. The structure according to claim 3 wherein the transparent conductive layer includes at least one of Zn, In, Sn, Cd, S, and O.
5. The structure according to claim 4 wherein the transparent conductive layer is a (Cd,Zn)S/transparent conductive oxide stack.
6. The structure according to claim 5 wherein the absorber layer is a Cu(In,Ga)(S,Se) 2 layer.
7. The structure according to claim 2 wherein the region over which the insulator film is disposed is over and along an edge of the substrate.
8. The structure according to claim 7 wherein the insulator film further covers the sidewall of the substrate along the edge.
9. The structure according to claim 8 wherein the insulator further covers an edge region of the bottom surface of the substrate along the sidewall.