Ferro Electronic Materials, a leading supplier of materials for fabricating photovoltaic silicon solar cells for more than 30 years, will introduce two series of metallization paste products enabling next generation high-efficiency cell technologies at PV Taiwan 2011, 5-7 October in Taipei, Taiwan. The materials include two new optimized silver contact pastes to enhance performance of Emitter Wrap Through (EWT) cell architectures and a family of silver pastes to enable cost-effective, high efficiency cells using n-type silicon wafers. The introductions complete Ferro's portfolio of 25 new products that have been commercialized in the second half of 2011.
Silver Contact Pastes for EWT Cells
EWT's back-contact technology is designed to increase the electrical efficiency of polycrystalline silicon-based solar cells by reducing front contact shadow loss. Ferro's new n- and p-contact pastes are capable of printing high definition lines to reduce material usage and cost, and are optimized for co-firing. Their high conductivity, low contact resistance and low recombination under contact areas improve efficiency, and they provide strong adhesion with EWT cell architectures. Ferro's NS 3165 EWT n-contact paste offers robust rheology that is suitable for through-hole applications and fine grid lines. It has good diode characteristics, low resistive loss, low leakage current, and fires through passivation layers. Ferro's PS 2166 EWT p-contact paste features heavy p doping for very low contact resistance. It provides ohmic contact and fires through passivation layers.
Silver Pastes for n-Type Wafers
N-type silicon wafers are less sensitive to common impurities than the traditional p-type wafers, offer long-term stability and are in plentiful supply. Due to similarities with p-type solar cell processing, this cell manufacturing technology is easy to implement into existing production lines. Ferro's new family of paste products for n-type wafers includes silver p-contact pastes, a silver n-contact paste, and a low-temperature polymer silver material. Ferro's silver p-contact pastes offer high aspect ratios and high Voc, low contact resistance, excellent bulk resistivity and excellent diode performance. They provide good solderability and are compatible with fast printing speeds. PS 2150 contacts deep emitters of 45-60 Ohms per square; PS 2151 contacts shallow emitters of 45-60 Ohms per square; and PS 2152 contacts shallow emitters of 45-65 Ohms per square. PS 2167 MWT is suitable as the p-contact and plug-hole paste for n-type Metal Wrap Through cell architectures.
Ferro's NS 3169 n-contact paste offers low contact resistance, low bulk resistivity, good solderability, and fires through a variety of back surface passivation layers. Ferro's LF 7123 low temperature polymer silver is a thermoset polymeric paste with enhanced printability. It offers lower contact resistance, higher bulk conductivity and excellent adhesion to fired aluminum emitters used on n-type wafers with front surface field.
"Next generation solar cell architectures such as EWT and n-type wafers require novel materials to achieve their potential electrical efficiencies, and these innovative new materials are designed to meet their specific needs," said Dr. Aziz Shaikh, Ferro director of photovoltaic R&D. "They are the most recent commercial products of our development efforts to support advanced technologies aimed at reducing solar energy's cost per Watt."