Enhanced hydrogenated silicon nitride (SiN_x:H) thin film as single layer anti-reflection (SLAR) coating in tunnel oxide passivated contact solar cells

This study presents an in-depth investigation into optimizing the silicon nitride (SiN_x:H) layer for Tunnel Oxide Passivated Contact (TOPCon) solar cells to enhance overall passivation and efficiency. Focusing on the SiN_x:H thin film, our research explores the effects of varying flow rates to achieve an ideal balance between surface passivation and anti-reflective properties. The optimized SiN_x:H layer deposited with an NH₃/SiH₄ flow rate of 1.3 exhibits a refractive index of 2.04 and a carrier lifetime of 625 μs reflecting an excellent passivation quality. However, transmittance of over 96.12 % is achieved with a bandgap of 3.01 eV under the same optimized condition. Using FTIR we observe the hydrogen concentration of SiN-H and Si-H as 8.96 × 10²² cm⁻³ and 6.74 × 10²² cm⁻³ indicating correlates with enhanced SiN_x:H bonding at 2.04 refractive index. Furthermore, an implied open-circuit voltage (iV_oc) of 714 mV contributes to an overall efficiency of 22.84 % of TOPCon solar cell, underscoring the critical role of fine-tuned SiN_x:H deposition in minimizing recombination losses. Through this approach, we demonstrate the targeted flow rate adjustments can significantly influence SiN_x:H properties, driving improvements in the passivation and optical performance essential for advancing high-efficiency TOPCon solar cells.