Summary 

Tools and inks for the atmospheric inkjet printing of Ag 

metallization for Si solar cells have been developed. 

Line widths, conductivities and thicknesses comparable to, or 

better than, those produced by screen printing. 

A new fire-through ink and layered printing were found to 

decrease the processing temperature for contact formation to 

as low as 650°C and improve printed cell performance. 

Future work: Improve resolution of printed lines, optimize firethrough layer thickness, processing time and temperature for 

best contacts. 

Multi-Layer Inkjet Printed Contacts for Si 

Solar Cells 

Calvin J. Curtis, Maikel F.A.M van Hest, Alex Miedaner, Tanya Kaydanova, 

Lee Smith, and David S. Ginley 

National Renewable Energy Laboratory, Golden Colorado 80401 

Objective 

To develop inkjet 

printing (including tools, 

inks, and processing 

conditions) for highquality Ag contacts for 

Si solar cells. 

Approach 

9Formulate inks using 

nanoparticle and/or 

metal-organic (MO) 

precursors + additives 

(surfactants, reducing 

agents, etc.) 

9Find optimal printing 

conditions 

(temperature, drop 

generation rate, drop 

volume, sample 

translation speed) 

9Find optimal 

annealing conditions 

(temperature, duration, 

gas ambient) 

Advantages of 

inkjet 

 Non-vacuum process 

 No contact between 

print head and

substrate 

 Liquid precursors 

– Good compositional 

control 

– Available for a 

variety of electronic 

materials 

– Multicomponent/Mult

ilayer printing 

 Efficient use of 

materials 

AFM of 1μm 

deep, 70μm wide 

trench produced 

by inkjet-printed 

“fire-through” 

agent onto an 

AR-coated Si 

wafer processed 

at 

650-750°C. 

Ag Printing with MO Ink 

Ink: MO Ag complex + solvent + surfactant, 

25% Ag by weight loading 

 Ag Deposition rate: 1μm/pass 

 Substrate temp: 180°C 

 Resolution: 85 μm for 1μm thick line, 220μm 

for 15 μm thick line 

 Resistivity: 2.2 μΩ⋅cm (1.6 μΩ⋅cm for bulk 

Ag) Screen Printing produces 10-20 μΩ⋅cm 

after firing 

Line thickness: 10 μm 15 μm 15 μm 

Line width: 400 μm 250μm 220μm 

Dep. Temp. : 180°C 180°C 180°C 

Ann. Temp.: 850°C 850°C 750°C 

Cell efficiency 8% 8% 10% 

AR-coated Si substrates from Evergreen 

Solar 

1st 

generation 

2nd 

generation 

1st 

2nd: 

Thicker 

contacts 

3rd:FireThrough 

Spray based processing has 

produced a 12% efficient cell 

Ag ink alone fires through the Si3N4 AR coating at 850°C to give 8% efficient cells 

MO “fire-through” ink was developed to facilitate penetration of Si3N4 layer 

Solar Cells with Printed 

Contacts 

Substrate 

X-Y 

Stage 

Ink 

Heating 

element 

Print head 

MicroFab Piezoelectric 

Inkjet Printer 

Al back 

contact 

Printed MO Fire- Printed Ag fingers Through Agent 

Si3N4 - Anti-Reflection 

Si p-n junction 

n

p

n

p

Contact forms at 

650°C 

Lowering the Processing Temperature: Layered 

Printing of a“Fire-Through” Agent 

U.S. Department of Energy 

Energy Efficiency and 

Renewable Energy 

Bringing you a prosperous 

future where energy is clean, 

abundant, reliable, and 

affordable 

The information contained in this poster is subject to a government license; 

NREL/PO-520-39919; 2006 IEEE 4th World Conference on Photovoltaic Energy 

Conversion; Waikoloa, Hawaii; May 7-12, 2006.