Ray Tracing of Light Trapping Strategies in Thin Silicon Solar Cells based on Tunnel Oxide Passivated Contact (TOPCon)

Tunnel oxide passivated contact (TOPCon) silicon (Si) solar cells, which utilise n-type silicon wafers, thin oxide layers, and polycrystalline silicon, are gaining popularity in photovoltaic industry due to its high efficiency potential. While 160 μm Si wafers are often used in current mass production, thinner wafers are projected to become mainstream in the future to reduce production costs. However, the decrease in the Si thickness reduces light absorptance, leading to lower device efficiency. Light-trapping strategies are utilised to enhance light absorptance in thin TOPCon cells and compensate for the efficiency loss. This work investigates light-trapping strategies in 100 μm-thin TOPCon cells using SunSolve. Upright pyramids with various heights and double layer anti-reflective coating (DLARC) silicon dioxide/silicon nitride (SiO2/SiNx), silicon oxynitride/silicon nitride (SiOxNy/SiNx) and aluminium oxide/silicon nitride (Al2O3/SiNx) with various thicknesses are examined to produce optimise average reflectance (Ravg), short-circuit current density (Jsc) and efficiency (η). From the results, the device with 5 μm front upright pyramids, SiO2/SiNx DLARC (60 nm/60 nm), and 1 μm rear upright pyramids exhibits Ravg, Jsc and η of 15.61%, 38.40 mA cm−2 and 21.02% respectively. The results demonstrate that the light-trapping strategies successfully enhance the efficiency of the thin TOPCon solar cells.