Improving the performance of high-efficiency silicon heterojunction solar cells through the synergism of composite passivation with energy-band engineering

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Abstract This study demonstrates the critical role of integrating energy band engineering with asymmetric composite passivation structures in enhancing silicon heterojunction (SHJ) solar cells performance. By investigating the effect of deposition pressure on the optical bandgap of pure silane passivation layers, tunable bandgap values ranging from 1.60 eV to 1.89 eV were achieved. This pressure-induced bandgap modulation enabled the implementation of asymmetric energy band engineering at the c-Si/a-Si:H interface, reducing the band offset from 0.61 eV to 0.36 eV and increasing the effective minority carrier lifetime by 29%. The optimized SHJ solar cells exhibited an open-circuit voltage (Voc) of 734.8 mV and a fill factor (FF) of 85.08%, reflecting respective improvements of 3.0% and 3.5%, and a power conversion efficiency (PCE) of 24.2% on G12 half-area wafers. These results confirm that energy band engineering of asymmetric composite passivation layers effectively balances passivation quality and carrier transport, significantly enhancing device performance.