A metal contact process improves solar cell efficiency to 26.31% by reducing energy losses and supporting large-scale production.
Researchers from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), in collaboration with Soochow University, Zhejiang Gonda Electronic Technology Co., Ltd., and JA Solar Technology Co., Ltd., have developed a new metallization method for tunnel oxide passivated contact (TOPCon) solar cells. The method achieved a certified power conversion efficiency (PCE) of 26.31%, among the highest reported for TOPCon solar cells, and a certified short-circuit current density (Jsc) of 41.98 mA/cm², which the researchers say is the highest reported for large-area TOPCon solar cells. The findings were published in Matter.
According to the researchers, the method addresses the long-standing trade-off between creating low-resistance electrical contacts and preserving the cell’s passivation layer. Because it is compatible with existing manufacturing processes, it could support large-scale production of more efficient TOPCon solar cells while reducing energy losses.
The challenge with conventional TOPCon manufacturing lies in the metallization process. High-temperature firing of silver-aluminium paste creates good electrical contacts but can damage the passivation layer and produce wider metal gridlines that block incoming light, limiting further improvements in cell efficiency.
To overcome this, the researchers combined an aluminium-free silver paste with a laser-enhanced contact optimization (LECO) process. The newly developed paste maintains narrow, tall gridlines after screen printing, reducing shading while protecting the passivation layer. The LECO process uses a laser to create localized heating that forms low-resistance electrical contacts without exposing the entire cell to high temperatures.
The researchers say this combination improves charge extraction while reducing metal-induced recombination losses. They believe the approach offers a practical way to improve the efficiency of TOPCon solar cells without requiring major changes to existing manufacturing, making it suitable for next-generation photovoltaic production.
