Brussels (Belgium), September 24, 2018 — At today’s EU PVSEC conference,  imec – the world-leading research and innovation hub in nanoelectronics,  energy and digital technology and partner in EnergyVille – announced  that its latest generation of large-area monofacial screen-printed  rear-emitter nPERT cells feature a conversion efficiency of 23.03  percent, certified by Fraunhofer ISE CalLab. The nPERT (n-type  Passivated Emitter and Rear Totally diffused) solar cells are made using  an industry-compatible screen-printing process that has been designed as an upgrade of conventional pPERC (p-type Passivated Emitter and Rear  Cell) processes. According to imec, its nPERT technology is projected to  reach 23.5 percent efficiency by the end of this year, and there is a  clear technology roadmap to eventually surpass 24 percent.

While p-type PERC solar cells are becoming mainstream in the PV  industry, n-type PERT technology is being developed as a cost-effective  contender that has a number of inherent advantages: Due to the absence  of B-O complexes, n-type cells don’t suffer from light induced  degradation (LID) and are less sensitive to metal impurities. That makes  for cells that have the potential for a longer-term stability and a  higher efficiency. Imec fabricated the M2-sized cells (area: 244.3 cm²)  on its pilot line with industry-compatible tools and recipes, in a  process that is an upgrade of the pPERC fabrication process, using a  similar layout of an n+ region (Front Surface Field) on the illuminated  side and a p+ region (as rear emitter) on the opposite side and adding a  cost-effective boron diffusion.

“Until now, nPERT solar technology has not yet found the traction it  deserves in the industry,” says Loic Tous, senior researcher at imec.  “With these ever-improving results, which we achieved by applying  knowledge gained from our bifacial nPERT project, we are now  demonstrating the potential of nPERT technology. The advantages in  stability and efficiency potential over p-type PERC cells, while using  the same equipment with the addition of a Boron diffusion, make this a  very promising technology for future manufacturing lines.”