| Summary: | In recent years, polycrystalline passivated emitter and rear cell (PERC) solar cells have developed rapidly, but less research has been conducted on the preparation process of their rear side passivation layers on standard solar cell production lines. In this work, a Al<sub>2</sub>O<sub>3</sub>/SiN<sub>x</sub> rear side stacked passivation layer for polycrystalline PERC solar cells was prepared using the plasma- enhanced chemical vapor deposition (PECVD) method. The effects of different Al<sub>2</sub>O<sub>3</sub> layer thicknesses (6.8~25.6 nm), SiN<sub>x</sub> layer thicknesses (65~150 nm) and SiN<sub>x</sub> refractive indices (2.0~2.2) on the passivation effect and electrical performance were systematically investigated, which were adjusted by TMA flow rate, conveyor belt speed and the flow ratio of SiH<sub>4</sub> and NH<sub>3</sub>, respectively. In addition, external quantum efficiency (EQE) and elevated temperature-induced degradation experiments were also carried out to check the cell performance. The results showed that the best passivation effect was achieved at 10.8 nm Al<sub>2</sub>O<sub>3</sub> layer, 120 nm SiN<sub>x</sub> layer and 2.2 SiN<sub>x</sub> layer refractive index. Under the optimal conditions mentioned above, the highest efficiency was 19.20%, corresponding V<sub>oc</sub> was 647 mV, I<sub>sc</sub> was 9.21 A and FF was 79.18%. Meanwhile, when the refraction index was 2.2, the EQE of the cell in the long-wavelength band (800–1000 nm) was improved. Moreover, the decrease in conversion efficiency after 45 h LeTID was around 0.55% under the different refraction indices. The above results can provide a reference for the industrial production of polycrystalline PERC solar cells.
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