by Riko Seibo
Tokyo, Japan (SPX) Mar 09, 2026
Crystalline silicon solar cells dominate the global photovoltaic industry, and tunnel oxide passivating contact (TOPCon) architectures are rapidly gaining market share because they offer strong performance while remaining compatible with existing manufacturing lines. Industrial TOPCon cells, however, have struggled to approach their theoretical conversion limits, with suboptimal electrical performance creating a persistent gap between mass production efficiencies and what the technology should achieve in principle.
A research team led by Prof. YE Jichun at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences has now reported a major advance that pushes industrial TOPCon performance to a new level. Working with collaborators from Zhejiang Jinko Solar Co., Ltd., Soochow University, and China Jiliang University, the team demonstrated an industrial-scale TOPCon solar cell with a certified power conversion efficiency of 26.66 percent. The results, obtained on an M10 crystalline silicon wafer with an effective area of 313.3 square centimeters, were published in Nature Energy on February 24.
The core of the advance is a dual-side electrical refinement strategy designed specifically for large-area TOPCon devices. On the front side of the cell, the researchers combined high sheet resistance boron emitters of about 430 ohms per square with an optimized grid design. This combination improves surface passivation and lowers carrier transport losses, helping the device retain more of the photogenerated charge carriers as usable current.
On the rear side, the team introduced a double-layer tunnel oxide and polysilicon structure intended to limit performance degradation caused by metallization processes. The structure consists of a highly crystalline inner polysilicon layer that maintains strong electronic contact with the silicon wafer and an outer barrier layer that blocks silver atoms from diffusing out of the metal electrodes into the silicon substrate. By preventing this silver diffusion, the design sustains excellent interfacial passivation and preserves the voltage characteristics of the cell during and after metallization.
The researchers also strategically thinned the rear polysilicon layer to raise the bifaciality of the device to 88.3 percent, allowing the cell to generate more energy when illuminated from both sides. Taken together, these engineering steps yielded an open-circuit voltage of 744.6 millivolts and a fill factor of 85.57 percent for the industrial TOPCon device. According to Prof. YE, the resulting cell has reached 83.8 percent of the theoretical efficiency limit for this technology and surpasses the performance of conventional TOPCon solar cells.
Research Report:Industrial tunnel oxide passivating contact solar cells with 26.66 percent efficiency
Related Links
Ningbo Institute of Materials Technology and Engineering (NIMTE)
All About Solar Energy at SolarDaily.com
