Synergistic enhancement of Nafion edge passivation and bifacial illumination for high-efficiency mechanically stacked c-Si solar cells

Enhancing the efficiency of silicon-based PV devices is critical for advancing solar energy technologies. This study investigates the impact of Nafion-based edge passivation and bifacial illumination optimization on mechanically stacked bifacial c-Si TOPCon solar cells. Nafion passivation at varying concentrations (2.5 wt%, 5 wt%, and 10 wt%) was applied to mitigate edge recombination losses, with 5 wt% identified as optimal, leading to efficiency enhancements of 27.96% for n-TOPCon and 28.47% for p-TOPCon under 1 sun front illumination with 0.5 sun rear albedo. The solar cells were mechanically stacked and analyzed under different electrical interconnections (parallel and series) and varying rear-side albedo levels (0.1–0.5 sun). The p-TOPCon tandem configuration achieved efficiencies from 21.80 to 28.47% (parallel) and 11.92–22.53% (series), while the n-TOPCon tandem exhibited 23.04–27.96% (parallel) and 9.34–18.27% (series). Results confirm that bifacial illumination significantly improves charge carrier collection and reduces recombination losses, particularly under high-albedo conditions. This study presents a scalable and cost-effective strategy for enhancing c-Si TOPCon solar cells, integrating bifacial light harvesting, Nafion passivation, and tandem stacking, offering promising potential for next-generation high-efficiency photovoltaics.