Engineering topics

Smith, Mitchell [Electroninks]

Publications and source records attributed to Smith, Mitchell [Electroninks].

3 records

DOE OSTI2026

Nickel Interlayer for Improved Silver Complex Inks Metallization in GaAs Photovoltaic Devices

Large areas of III-V photovoltaic panels are essential to supplying operational energy for a growing demand of satellites of strategic importance to the United States military, covering a range of applications. High fabrication costs and low manufacturing throughput are key barriers to meeting the necessary supply, which can in turn jeopardize mission success. At the device level, metallization based on printing of complex metal inks has attracted significant research interest due to its potential to substantially reduce processing costs and increase throughput while achieving electrical performance comparable to those of conventional metallization schemes. For GaAs photovoltaic devices, however, reliable electrical contacting remains challenging due to the formation of an interfacial oxide layer at the metal-semiconductor interface. This oxide barrier severely limits current extraction from the PV absorber, resulting in unacceptably high contact resistance. In this study, we report the introduction of a reactive nickel (Ni) interfacial layer between the silver metal fingers and the GaAs substrate to suppress oxide formation while maintaining a low-resistance electrical interface, and show performance data from fully fabricated GaAs devices incorporating the Ni interlayer. These results demonstrate the potential of reactive Ni ink as an effective interfacial layer for improved electrical contacting in low-cost PV metallization schemes.

14 SOLAR ENERGY↗

DOE OSTI2026

Screen-Printed SHJ Solar Cells with Complex Silver Inks

Metallization using complex metal inks has gained significant research interest due to its cost-effectiveness and ability to achieve performance comparable to traditional nanoparticle pastes. This study introduces the use of complex silver (Ag) inks applied via industrial screen-printing for silicon heterojunction (SHJ) solar cell metallization. The printed Ag lines exhibit a contact resistivity on SHJ tin-doped indium oxide (ITO) surfaces as low as approximately 0.2-12 mO cm2. Photoluminescence imaging reveals minimal surface passivation degradation (iVoc < 3.5 mV), while scanning electron microscopy (SEM) shows a denser structure compared to Ag layer from nanoparticle pastes. The printed Ag grid features thin (approximately 1 micrometer), continuous fingers approximately 100-120 micrometer wide, significantly thinner than conventional approximately 20-30 micrometer fingers produced with nanoparticle-based pastes. Double printing achieves SHJ device efficiencies exceeding 20%, the highest reported for industrial solar cell precursors using this technology. These findings highlight the potential of complex Ag inks as a sustainable alternative to particle-based pastes, reducing Ag consumption and processing temperatures without compromising efficiency.

14 SOLAR ENERGY↗

DOE OSTI2025

Low-Cost, Screen-Printed Silver Metal Complex Inks for Silicon Heterojunction Solar Cells

Screen printing using metal particle pastes, the current photovoltaic industry metallization standard, provides fast and reliable metal grids for silicon solar cells. Recently, metal complex or reactive metal inks are attracting research interest due to their significantly low cost and higher performance compared to traditional nanoparticle silver pastes. In this work, we demonstrate, for the first time, screen-printed high-efficiency silicon heterojunction solar cells metallized by silver metal complex inks on industrial G1-size (158.75 x 158.75 mm2) wafers. We demonstrate screen-printed Ag metal complex ink grid patterns with continuous fingers ~100-120 ..mu..m wide. The printed Ag grid is very thin (~1 ..mu..m), which is an order of magnitude thinner than the current ~20-30 ..mu..m fingers printed with low-temperature nanoparticle-based pastes. Double printing allows silicon heterojunction devices with efficiencies >20%. This is the highest efficiency so far, to our knowledge, of industrial solar cell precursors using this metallization technology. Simulation results suggested that increasing the thickness of the metal film does not significantly improve efficiency due to the dense, highly conductive films. So, a single print of ~1 ..mu..m finger would be enough to produce cells that perform similarly to a ~20 ..mu..m thick nanoparticle paste printed cells. Additionally, solar cells printed on G1 wafers with silver metal complex ink required more than 10 times less silver (~0.03 g) compared to those using silver/copper nanoparticle paste (~0.4 g of Ag). These results indicate that metal complex inks are a very promising replacement for silver nanoparticle pastes for industrial-scale metallization in an age of resource scarcity and high costs of noble metals.

14 SOLAR ENERGY↗