Simulation of Silicon Solar Cells with Passivation Contact of Tunnel Oxide Layer

The paper deals with the influence of the oxide thickness, of the pinhole density through the oxide layer, and of the doping concentration of poly-Si on the performance of crystal silicon solar cells with a passivation contact of the tunnel oxide layer. The efficiency of double-sided tunnel oxide passivated contact (TOPCon) solar cells is slightly lower than that of metal insulator semiconductor (MIS) solar cells, which results from the defect recombination in heavily doped poly-Si layers of TOPCon solar cells. Without considering the density of pinholes in the oxide layer, the efficiency of TOPCon (or MIS) solar cells is 24.3% (or 25.4%) when the oxide thickness is 1.0 nm. However, in the case of a suitable pinhole density (10–5—10–6) in the oxide layer, the device efficiency as high as 24.0% can be obtained, and it is almost independent of the oxide thickness, which results from the recombination current that dominates in the case of a suitable pinhole density. A suitable pinhole density in the oxide layer and heavy doping in the poly-Si layer may help to reduce the sensitivity of device performance to the thickness of silicon oxide, and the carrier-selective passivation contact holds the potential for simplified solar cell manufacturing while providing very high conversion efficiencies.