Solar cell interconnection
Methods and devices for solar cell interconnection are provided. In one embodiment, the method includes physically alloying the ink metal to the underlying foil (hence excellent adhesion and conductivity with no pre-treatment), and by fusing the solid particles in the ink on the surface (eliminating any organic components) so that the surface is ideally suited for good conductivity and adhesion to an overlayer of finger ink, which is expected to be another adhesive. In some embodiments, contact resistance of conductive adhesives are known to be much lower on gold or silver than on any other metals.
1. A method of solar cell manufacturing, the method comprising:
providing a photovoltaic device layer having a plurality of vias therethrough;
partially filling the vias with a liquid, electrically conductive material;
heating the liquid, electrically conductive material with sufficient energy to fuse a portion of metal foil underneath the vias with solid ink components in the liquid, electrically conductive material with the metal foil to form a metal alloy; and
filling the vias with additional electrically conductive material.
2. The method of claim 1 wherein solar cell has a metal wrap through (MWT) structure.
3. The method of claim 1 wherein the liquid, electrically conductive material comprises a silver-containing ink.
4. The method of claim 1 further comprising drying the liquid, electrically conductive material to make the material solvent-free.
5. The method of claim 1 wherein heating comprises irradiating with a pulsed laser with sufficient energy.
6. The method of claim 1 wherein solid ink components comprises silver particles.
7. The method of claim 1 wherein the metal foil comprises aluminum foil underneath.
8. The method of claim 1 wherein solid ink components comprises silver particles and the metal foil comprises aluminum foil underneath, creating an Ag—Al alloy.
9. The method of claim 1 heating comprises using a pulsed laser.
10. The method of claim 1 wherein partially filling forms a layer with a thickness between 1 and 10 microns in the vias.
11. The method of claim 1 wherein the liquid, electrically conductive material comprises conductive adhesive with polymer binder.
12. The method of claim 1 wherein organic material in the liquid, electrically conductive material is vaporized during heating.
13. The method of claim 1 the liquid, electrically conductive material comprises inorganic glasses surrounding silver particles.
14. The method of claim 1 comprises alloying metal in the liquid, electrically conductive material to the metal foil.
15. The method of claim 1 comprises fusing solid particles in solid ink components.
16. The method of claim 1 comprises no pre-treatment of the metal foil to remove oxides.
17. The method of claim 1 wherein fully filling the vias uses an electrically conductive material different from the liquid, electrically conductive material.