In this paper we will present two approaches for the frontside metallization of crystalline silicon solar cells, targettting on dramatically reducing the specific contact resistance between the metal gridline and the n+ emitter layer. The first one is to use a blanket sputtered Ni film as the contact layer and screen printed Ag lines as an etch mask to pattern the underlying Ni film. The experimental result shows that, the specific contact resistance with this approach can be reduced by almost two orders of magnitude compared to only using screen printed Ag gridlines. In order to further reduce the cost for introducing the Ni contact layer, using inkjet printed Ni nanoparticle ink to form the contact layer is also studied. It has been shown that, with well controlled printing and annealing conditions, the printed Ni ink approach can achieve almost the same contact resistance as that using sputtered Ni film. The signficant reduction on contact resistance can increase the absolute cell efficiency by up to 0.9%, according to the PC1D modeling result.
Xu, B.; Limb, S.; Rodkin, A.; Garner, S.; Shrader, E. Improvement of silicon solar cell metallization with printed nickel nanoparticle ink. TechConnect World 2012; 2012 June 18; Santa Clara, CA, USA.