Numerical analysis of p-type and n-type based carrier-selective contact solar cells with tunneling oxide thickness and bulk properties

Tunnel Oxide Passivated Contact (TOPCon) is a c-Si solar cell structure with tunneling oxide near the rear electrode. A full-area tunneling oxide provides sufficient passivation and low internal resistance with 1D carrier transport. Carrier tunneling mechanism is the key factor of a TOPCon solar cell; the thicker the tunneling oxide, the better is its ability to prevent minority-carrier tunneling. However, excessively thick oxide degrades majority-carrier tunneling. Therefore, the relationship between tunneling oxide thickness and cell performance is important. In this study, TOPCon solar cell structures are evaluated by varying their tunneling oxide thickness and bulk properties for both p-type and n-type bulk using numerical simulation. It is observed that the difference in bulk type is crucial to TOPCon solar cell performance: n-type material shows better performance because of its smaller minority-carrier tunneling current density and wider range of effective tunneling oxide thickness compared to p-type.