# Dual-Oxide Barrier Enhances TOPCon Solar Cell Efficiency New oxidation process improves solar cell performance by shifting phosphorus peaks for better conductivity. - **Source:** [pv magazine](https://www.pv-magazine.com) - **Published:** 2026-11-10 - **Topic:** [science](https://brifing.si/c/science) - **Original article:** - **On Brifing:** https://brifing.si/s/b8134c7b-02b1-4278-85b1-91cab3028ce9 ## New Diffusion Barrier Strategy Researchers at Nanchang Hangkong University developed a dual silicon oxide diffusion barrier strategy to enhance TOPCon solar cell efficiency. By combining post-plasma oxidation with tunnel oxide optimization, the team successfully controlled the depth distribution of electrically active phosphorus. This method addresses critical trade-offs between contact resistance and parasitic optical absorption in cells. ## Optimizing Phosphorus Depth Distribution Conventional industrial processes often struggle with phosphorus accumulation at the polysilicon surface, which increases unwanted optical absorption. The team's post-plasma oxidation technique shifts the activated phosphorus peak from 20 nm to 50 nm deep. This precise depth adjustment aligns closely with silver paste burn-off depths during the screen-printing and co-firing stages. ## Mechanism of Dopant Deactivation The process utilizes inward-diffusing oxygen to induce depth-selective dopant deactivation through the formation of electrically inactive phosphorus-oxygen complexes. Rather than physically moving phosphorus atoms, this chemical approach maintains high dopant activation levels. Extending the post-plasma oxidation duration to 100 seconds proved optimal for balancing passivation quality and electrical performance in tests. ## Industrial Scale Validation Results Testing involved 966 mass-produced TOPCon cells measuring 210 by 182.3 mm. The optimized oxidation process resulted in an absolute efficiency gain of 0.07 percentage points, raising average conversion from 27.15% to 27.22%. This improvement was primarily driven by a higher fill factor and increased short-circuit current across the tested batch. ## Reduced Contact Resistivity Achieved The researchers observed a significant decrease in contact resistivity, dropping from 1.54 mΩ cm² to 1.00 mΩ cm². While the exact contribution of the phosphorus peak shift remains complex to isolate, the reduction in parasitic absorption clearly improved the long-wavelength response. Minor degradation in open-circuit voltage was noted but offset by gains. ## Compatibility With Existing Lines This modification is designed for implementation on existing plasma-enhanced chemical vapor deposition production lines. By adjusting oxidation durations and densifying the bottom tunnel oxide, manufacturers can adopt this method without major hardware overhauls. The study highlights a practical route for improving commercial solar cell performance using standard industrial fabrication equipment. ## Material Characterization and Analysis The team utilized advanced techniques including secondary ion mass spectrometry and electrochemical capacitance-voltage profiling to map elemental distributions. X-ray diffraction and Raman spectroscopy confirmed that the polysilicon crystallinity remained largely unchanged despite the oxidation treatment. These insights provide a comprehensive understanding of how the dual-oxide barrier influences the cell's microstructure. ## Future Implications for Photovoltaics Published in the journal Solar Energy, this study demonstrates that simple process modifications can yield measurable efficiency improvements in mass-produced photovoltaics. Future research will likely focus on isolating the individual contributions of structural changes versus optical effects. This work represents a step forward in refining high-efficiency TOPCon solar cell manufacturing technology. ## Sources covering this story - https://www.pv-magazine.com/2026/11/10/dual-oxide-diffusion-barrier-boosts-efficiency-of-mass-produced-topcon-solar-cells-by-0-07-percentage-points/ — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._