Non-volatile free silver paste formulation for front-side metallization of silicon solar cells

Abstract

We present a versatile, cost-effective formulation platform for highly conductive silver pastes used in front-side metallization of silicon (Si) solar cells. Pastes based on the capillary suspension concept include silver particles, glass frit and two immiscible fluids. Capillary forces inferred from the second fluid added only in small fractions induce the formation of a percolating particle network. This provides extended shelf-life and distinct flow properties adjustable in a wide range as demanded by the respective printing process, thus yielding residual-free sintered electrodes. Si-wafers are successfully metallized with such pastes using conventional screen-printing, knotless screen and Pattern Transfer Printing™. Paste spreading is studied via high-speed imaging during screenprinting on glass plates. Morphology of printed lines is analyzed using laser scanning microscopy. Electrical properties of the cells are characterized employing a solar simulator and electroluminescence spectroscopy. Results are compared to those obtained using commercial pastes including the same silver particles and glass frits. Paste performance strongly depends on the selected secondary fluid. Aspect ratios ≈0.4-0.5 can be reached and cell efficiencies η eff ≈ 21% on Cz-and 18.6% on mc Si-wafers are obtained. Additional investigations are necessary to further reduce paste spreading and line interruptions thus improving cell performance.

Printing technologies for silicon solar cell metallization: A comprehensive review

“…The ongoing development of metal pastes, especially silver fire‐through pastes for PERC, low temperature Ag‐pastes for SHJ metallization, and aluminum high temperature pastes for fully or structured rear side metallization, played a major role for the success story of flatbed screen printing in the PV industry. Commonly industrial available Ag‐pastes for front side metallization of PERC contain a mass share of up to 95% Ag‐particles with average particle sizes of 3–4 μm and a more or less spherical shape 277,303 . Additionally, glass frits, based on quartz glass containing lead oxide, are added, which serves on the one hand the purpose of a glue between the substrate and the printed contact line and furthermore enables the contact formation by etching the silicon nitride anti‐reflection coating on the wafer surface (see Section 3 for more details) 304,305 .…”

Nutzung rheologischer Kennwerte zur Beurteilung der Schmierfetteignung bei tiefen Temperaturen

“…Für andere Stoffsysteme, wie z. B. Silberpasten 12, 13 hat sich die Verwendung einer Flügelrad‐Geometrie bewährt. Die Fließgrenzen der Fette TMSE 11, PAG 11 und MOE 11 wurden mittels Flügelrad‐Geometrie ( d = 10 mm, Länge l = 22 mm) an dem Rheometer MARS (Thermo Fisher Scientific) in stetiger Scherung bestimmt.…”

Performance of plasma source and irradiation for optical properties improvement of gelatin/silver composite

“…Currently, metallization of solar cells and photovoltaic applications utilize roughly 7.5 % of the world's silver output [49,50]. A straightforward, adaptable, and affordable manufacturing platform for highly conductive silver pastes suitable for various printing technologies used in front-side metallization of silicon solar cells and is the formulation of non-volatile free silver paste based on the socalled capillary suspension concept.…”