Optimization of multilayer antireflection coatings on the front surface of N-type TOPCon solar cells

The application of antireflection film can reduce the Fresnel reflection at the gas-solid interface, representing an effective method of improving the power conversion efficiency of crystalline silicon solar cells. The N-type Tunnel Oxide Passivated Contact (TOPCon) solar cells typically employ AlOx/SiNx as the antireflection film, but the thickness adjustment range of the AlOx layer is limited by the passivation effect, so the adjustment of the antireflection effect depends more on the SiNx layer. In this paper, to solve the problem of refractive index matching, the SiNx/SiOx and SiNx/SiOxNy/SiOx antireflection stacks were proposed. Compared with the SiNx monolayer, SiNx/SiOx and SiNx/SiOxNy/SiOx stacks can significantly reduce the photon reflectivity in the wavelength range of 300-500 nm, and the antireflection effect was better in the short wavelengths. Compared with the electrical performances of traditional solar cells only with SiNx layer, the power conversion efficiency of the cells with SiNx/SiOx stack reached 24.68%, and the cells with SiNx/SiOxNy/SiOx stack reached 24.78%, which was 0.2%abs. and 0.3%abs. higher than the former respectively. The film thickness of theSiN(x)/SiOxNy/SiOx stack layer was further optimized, ultimately determining that the thickness of SiNx/SiOxNy/SiOx was 60 nm/10 nm/15 nm, respectively. The optimum thickness combination of the antireflective coating in this study provides insights into achieving a conversion efficiency of 24.84% for TOPCon solar cells.