Improving Passivation Performance and Efficiency of N-Topcon Solar Cell Bylight Soaking Process

In this study, we investigate the emitter dark saturation current density under the passivation layer (J0), the metallization-induced recombination under the metal contact (J0,metal), surface recombination velocity (Seff), contact resistivity (ρc), the ratio of Si-H content under the passivation layer and the I–V parameters as function of the light soaking process. The results showed that the light soaking process had less impact on J0 of p+ layer and SiOx/n+-poly-Si layer, only decreased the values of Seff on p++ layer about 8.67 cm/s. However, it had the greatest impact on the metallization-induced recombination of p++ layer and the Si substrate with a corroded Ag with the depth of over 165nm in Si substrate, by breaking the bending of (Si:H2)n bonds under light soaking, leading to a transition of H from the bound state of Si-H bonds to the free state, then captured the movable Ag and boron atoms at the surface of the wafer surfaces to passivation. While the passivation enhancement of the metallization-induced recombination of SiOx/n+-poly-Si layer without Ag etching the n+-poly-Si layer, by cleaning excess H to prevent the formation of new defects. There was an efficiency gain of 0.87% mainly owing to the increase in Voc, Jsc and FF values of 10 mV, 0.15 mA/cm2 and 1.5%, respectively. This research contributes to a deeper understanding of light Soaking performance changes in SiNx:H film. Finally, we manufactured industrial-grade TOPCon cells with Eff, Voc, Jsc, and FF values as high as 25.8%, 729 mV, 42.1 mA/cm2, and 84%, respectively.