Improved front side metallization by aerosol jet printing of hotmelt INKS

The rheology of a low viscous aerosol ink was modified into a hot melt ink by substituting the original solvent system by a thermo plastic alcohol. Additionally the aerosol printer was adapted to hot melt printing by heating all parts which are in contact with the ink, including the atomizer, virtual impactor, printing head and atomization gas. Front side contacts on silicon solar cells were printed with a metal aerosol jet printer using this hotmelt ink. Improved line resolution, higher aspect ratio and higher solid content compared to conventional aerosol inks could be achieved. To demonstrate the industrial feasibility, a multi-nozzle printing system was used. Line widths of 40 µm could be achieved. The aspect ratio of the fingers is increased from 1:40 to 1:6. Large-area multicrystalline silicon solar cells were, printed at room temperature at different printing speeds, fired in an in-line belt furnace and finally plated in an industrial plating machine. Energy conversion rates as high as 16.1% were achieved. The short-circuit current and the fill factor of these cells is around 34 mA/cm2 and 78%, respectively, showing the excellent contact geometry of the fabricated fingers.