Metallization of Silicon Heterojunction Solar Cells by Copper Paste Dispensing

Abstract

In terms of global photovoltaic (PV) manufacturing capacity, crystalline silicon (c-Si)-based technologies account currently for 95% of the market, and one the most efficient technologies, among them, is the silicon heterojunction (SHJ) solar cell technology (efficiency above 26%). Nonetheless, this silicon-based photovoltaic is experiencing a threat due to the increasing price of silver, which is influenced by its shortage. For SHJ solar cells, silver usage for metallization accounts for approximately 25% of the total solar cell processing cost due to its large silver consumption. The findings emphasize that dispensed copper is a great alternative to silver for SHJ solar cell application, and it has a strong potential to reduce costs and improve cell efficiency. However, there are still obstacles to address for this technology. On one hand, dispenser printing technology needs to be improved in terms of printing quality, and on the other hand, copper reliability in terms of adhesion and electrical performance needs to be addressed. This research focuses on studying the characteristics of a single print dispensing, the process conditions of dispensed copper, the effect of those conditions applied to SHJ solar cells, and lastly the performance study of SHJ solar cells metalized with dispensed copper, then their comparison to other printing technology such as screen printing. It was found that dispensed Cu still has higher line resistance to screen-printed silver and that SHJ solar cells degrade above 280 ̊C and 5 s sintering conditions, though we could partly recover some loss with light soaking. SHJ solar cells metalized with dispensed Cu achieved an efficiency of>23% and a Voc of about 740 mV. This study advances SHJ solar cell technology by providing insights into the future potential of using dispensed copper metallization for improved and cost-effective solar cells.