Amorphous-silicon solar cells with screen-printed metallization

The use of screen printing for the back-side metallization of amorphous-silicon solar cells on glass is proposed. Compared with the conventional aluminum evaporation process, screen printing is attractive because if offers high throughput and because direct patterning is performed during the printing process. The critical point in realizing a thick-film screen-printed contact on amorphous-silicon solar cells is found to be the contact resistivity between the contact and the n-layer. Contact resistivities below 1 Ω-cm² have been obtained using a microcrystalline instead of an amorphous n⁺ layer and a screen-printed contact based on Mo, Ti, or Ni. Amorphous-silicon solar cells with a screen-printed back contact had a performance comparable with that of cells with an evaporated Al contact, resulting in an efficiency of 9.7%. Spectral response measurements demonstrated that the screen-printed contact is an efficient reflector of long-wavelength photons, resulting in a high red response due to internal light trapping