Record 26.31% efficiency TOPCon solar cells made with lasers and custom paste

A new study has improved the power conversion rate of Tunnel Oxide Passivated Contact (TOPCon), which are an advanced type of silicon solar cell. Particularly, the dual-action metallization strategy pushed industrial TOPCon silicon cells to a certified power conversion efficiency of 26.31 percent. Typically, TOPCon solar cells lose efficiency during metallization because high-temperature firing damages the passivation layer and requires thick gridlines that block light. A new strategy pairing aluminum-free silver paste with laser-enhanced contact optimization (LECO) solves this by using precise laser activation instead of heat. The development comes from the Ningbo Institute of Materials Technology and Engineering (NIMTE) under the Chinese Academy of Sciences alongside Soochow University. “The new approach resolves the intrinsic trade-off between contact resistivity and passivation preservation without compromising manufacturability, providing a practical route toward the industrialization of next-generation high-efficiency photovoltaic technologies,” the team stated in the press statement. Double-edged sword of solar heat TOPCon solar panels dominate the global market because these can be manufactured on existing production lines with minimal retooling. But the high efficiency relies on an ultra-thin oxide cushion beneath the electrical contacts, which prevents captured electrons from recombining and preserves the energy absorbed from sunlight. The flaw was in the finish. Conventional manufacturing prints a silver-aluminum paste on the surface and fires the cell in a high-temperature furnace. The aluminum spikes downward. It bites through the protective passivation layer and deforms the silicon emitter beneath. To make matters worse, the runny paste spreads wide during firing, blocking precious incoming sunlight. The team prevented cell damage by pairing an aluminum-free silver paste with Laser-Enhanced Contact Optimization. Notably, the specialized, high-retention paste forms ultra-thin, tall gridlines with a 55 percent aspect ratio that eliminate aluminum spiking while reducing light shading. Meanwhile, single-frequency lasers under reverse voltage bias precisely weld low-resistance silver contacts at micro-sites. It replaces high-heat roasting and preserves the underlying crystal structure. Enabled by the custom paste, the crucial passivation layer are safeguarded from the severe lattice disruption and aluminum alloying damage caused by existing high-temperature firing. Highest current recorded Overall, the technique worked. The design yielded a record-breaking short-circuit current density of 41.98 mA/cm² by maximizing light absorption and preventing charge leakage. As per the researchers, this density is “the highest certified Jsc reported for large-area TOPCon solar cells to date.” The development shows that minimizing optical shading and protecting the passivation layer directly translates into maximum current extraction. Furthermore, the team says that the process could be easily integrated into existing assembly lines. Hence, it could avoid changing the expensive factory infrastructure. And bonus, it delivers a rare trifecta for solar energy: cheaper power, improved long-term stability, and maximum sunlight utilization. Factories, warehouses, logistics hubs, and office buildings depend on TOPCon panels to maximize energy yield within limited roof space. By producing more kilowatt-hours per square foot, these panels allow commercial properties to optimize long-term power generation across a 25- to 30-year operational lifespan. The study findings were published recently in the journal Matter on August 6. Recommended ArticlesGet the latest in engineering, tech, space & science - delivered daily to your inbox.Mrigakshi is a science journalist who enjoys writing about space exploration, biology, and technological innovations. Her work has been featured in well-known publications including Nature India, Supercluster, The Weather Channel and Astronomy magazine. If you have pitches in mind, please do not hesitate to email her.