90% Silver Reduction in Silicon Heterojunction Cell Metallization with Reactive Silver Inks

Silver is the most expensive non-silicon component in photovoltaic cells. This is particularly salient for Silicon Heterojunction (SHJ) cells which can consume between 200-400 mg of silver in low-temperature silver pastes. Replacing low-temperature silver pastes with reactive silver ink can reduce silver consumption by producing more conductive fingers and lower contact resistances while avoiding high temperatures that can damage SHJ cells. This work investigates ink formulation and optimization for SHJ cells with a focus on PV performance and reduced silver consumption. We test reactive silver inks with different dominant reduction pathways, additives, and printing temperatures and characterize the silver fingers using electrical measurements and top-down and cross-section microscopy. The best performing ink achieved silver fingers with resistivities of 3.1 µΩcm and contact resistivities of 3.2 mΩcm² when printed at 61 °C. A 156 mm × 156 mm SHJ cell metallized with this reactive ink showed similar cell performance to low-temperature silver pastes while consuming 80-90% less silver.