Crystalline silicon solar cells currently dominate the global photovoltaic industry, with tunnel oxide passivating contact (TOPCon) technology—a type of architecture within this product segment—rapidly gaining market share due to its cost-effectiveness and compatibility with existing manufacturing processes. However, the efficiency of industrial TOPCon cells has long been constrained by suboptimal electrical performance, creating a persistent gap between mass-production efficiency and the technology's theoretical limit.
Now, Chinese scientists have made a major breakthrough in TOPCon technology that sets a new power conversion efficiency (PCE) record of 26.66% for industrial-scale solar cells.
The study, which was was led by Prof. YE Jichun from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences, in collaboration with scientists from Zhejiang Jinko Solar Co., Ltd., Soochow University, and China Jiliang University, was published in Nature Energy on February 24.
The core breakthrough was the development of a dual-side electrical refinement strategy for large-area TOPCon solar cells, using an M10 wafer with an effective area of 313.3 cm2.
On the cell's front side, the researchers paired high-sheet-resistance boron emitters (~430 Ω sq-1) with optimized grid designs, enhancing surface passivation and reducing carrier transport losses. On the rear side, they developed a novel double-layer tunnel oxide/polysilicon structure to mitigate metallization-induced degradation. The solar cell design features a highly crystalline inner polysilicon layer and an outer barrier layer that effectively blocks silver diffusion from the electrodes into the silicon substrate, ensuring excellent interfacial passivation.
Strategic thinning of the rear polysilicon layer further boosted the cell's bifaciality to 88.3%, improving overall energy yield. These synergistic innovations enabled the industrial TOPCon solar cell to achieve an open-circuit voltage (Voc) of 744.6 mV and a fill factor (FF) of 85.57%.
"The device has reached 83.8% of the theoretical efficiency limit, outperforming conventional TOPCon solar cells," said Prof. YE, a corresponding author of the study.
The findings establish a comprehensive pathway for manufacturing high-efficiency industrial TOPCon cells, narrowing the gap between their actual and theoretical efficiency while strengthening the technology's competitiveness in the global photovoltaic market.
