A research team at the Fraunhofer Institute for Solar Energy Systems ISE has set a new conversion efficiency world record of 26% for both-sides-contacted silicon solar cells.
The team led by Armin Richter has achieved the milestone with a solar cell based on the TOPCon (Tunnel Oxide Passivating Contact) technology, combining the benefits of very-low surface recombination losses with efficient charge carrier transport. The particular cell has the pn junction on the back side rather than the front, thereby eliminating the necessity of having the full-surface boron doping on the front side. This allows for higher voltages and higher fill factors.
The record-breaking TOPCoRE (TOPCon Rear Emitter) cell has approached the estimated potential of 27% for both-sides-contacted solar cells, established as the industry standard, and the theoretical efficiency limit of crystalline silicon of 29.4%. Fraunhofer ISE notes that previous record efficiencies of around 26% were only achieved with solar cells having both metal contacts at the rear, also known as interdigitated back contact (IBC) solar cells.
Richter explains the structure of the record-breaking cell in the recently published Nature Energy article "Design Rules for High-Efficiency Both-Sides-Contacted Silicon Solar Cell with Balanced Charge Carrier Transport and Recombination Losses."
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