Defect-passivated SiOx coating enabling significant ITO cost reduction with boosted efficiency and environmental stability in HJT solar cell

Heterojunction(HJT) solar cells face challenges associated with long-term stability, limited power conversion efficiency (PCE), and high manufacturing cost, which hinder their large-scale commercialization and practical application. This study investigates the optimization of the ITO layer and the development of a non-conductive anti-reflection film. By controlling the ITO thickness (40-60 nm) via magnetron sputtering and depositing a SiO x anti-reflection layer containing vacancies using PECVD, the solar cell performance is improved and the cost is reduced. The results demonstrate that the SiO x layers with a thickness of ≤20 nm facilitate efficient electron transport, while their surface passivation and defect-healing effects reduce defects at the ITO interface, thereby lowering the series resistance and improving fill factor (FF). Optical simulations and experimental results demonstrate that the ITO thickness 40-60 nm combined with SiO x layer thickness 60-100 nm achieves the highest PCE. Among them, the cells with a 60 nm-thick ITO layer exhibited a 0.38% improvement in efficiency after SiO x coating compared with the control group. In contrast, the cells with a 40 nm-thick ITO layer showed a 0.17% enhancement while reducing the ITO consumption by ~ 50%. Quantum efficiency (QE) analysis shows that SiO x significantly enhances UV-visible light band absorption, and the J S C increases by 0.44 mA/cm 2 . During the stability test, the SiO x layer effectively suppressed cell degradation in the acetic acid/sodium ion environment, while no significant performance degradation was observed under prolonged UV irradiation. Module-level validation demonstrates that the coated solar cells retain their efficiency enhancement after module integration, resulting in a power gain of 5.5W compared with conventional modules. The collaborative optimization of ITO thinning and SiO x coating simultaneously enables material cost reduction, enhanced PCE, and improved environmental stability. This strategy holds significant potential for practical application in the PV industry.