Performance of Large Area n-TOPCon Solar Cells with Selective Poly-Si Based Passivating Contacts Prepared by PECVD Method

Selective emitter (SE) technology significantly influences the passivation and contact properties of n-TOPCon solar cells. In this study, three mask layers (SiO_x, SiN_x, and SiO_xN_y) were employed to fabricate n-TOPCon solar cells with phosphorus (P)-SE structures on the rear side using a three-step method. Additionally, phosphosilicon glass (PSG) was used to prepare n-TOPCon solar cells with P-SE structure on the rear side using four-step method, and the comparative analysis of electrical properties were studied. The SiO_x mask with a laser power of 20 W (O2 group) achieved the highest solar cell efficiency (E_ff, 24.85%), The open-circuit voltage (V_oc) is 2.4 mV higher than that of the H1 group, and the fill factor (FF) is 1.88% higher than that of the L1 group. Furthermore, the final E_ff of solar cell is 0.17% higher than that of the L1 group and 0.20% higher than that of the H1 group. In contrast, using the four-step method and a laser power of 20 W (P2 group), a maximum E_ff of 24.82% was achieved. Moreover, it exhibited an V_oc, which is elevated by 3.2 mV compared to the H1 group, and FF increased by 1.49% compared to the L1 group. Furthermore, the overall E_ff of the P2 group outperforms both the L1 and H1 groups by approximately 0.14% and 0.17%, respectively. In the four-step groups, the E_ff of each laser condition group was improved compared with the L1 group and H1 group, The stability observed within the four-step method surpassed that of the three-step groups. However, in terms of full-scale electrical properties, the three-step method can achieve comparable results as those obtained from the four-step method. This research holds significant guiding implications for upgrading the n-TOPCon solar cell rear-side technology during mass production.