Influence of Al2O3/SiNx Rear-Side Stacked Passivation on the Performance of Polycrystalline PERC Solar Cells

Abstract

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 Al2O3/SiNx 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 Al2O3 layer thicknesses (6.8~25.6 nm), SiNx layer thicknesses (65~150 nm) and SiNx 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 SiH4 and NH3, 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 Al2O3 layer, 120 nm SiNx layer and 2.2 SiNx layer refractive index. Under the optimal conditions mentioned above, the highest efficiency was 19.20%, corresponding Voc was 647 mV, Isc 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.

TiO2 Thin Films by Atmospheric Pressure Chemical Vapor Deposition for Rear Surface Passivation of p-PERT Solar Cells

“…For instance, due to the lower parasitic absorption and better rear-side passivation, the sample with SiN X / SiO X N Y /SiN X stacks showed an enhancement of conversion efficiency by 0.09% when compared to the sample passivated with a single 80 nm thick SiN X film. Fan et al 8 analyzed an Al 2 O 3 /SiN X rear side stacked passivation layer obtained by plasma enhanced chemical vapor depositon (PECVD) for multicrystalline PERC solar cells. The results indicated that the most effective passivation was achieved with a 10.8 nm thick Al 2 O 3 layer and a 120 nm thick SiN X layer.…”

“…If the thickness of Al 2 O 3 was decreased to 6.8 nm or increased to 16 nm, the efficiency was reduced by 0.05% and 0.10%, respectively. If the film thickness of SiN X was reduced to 100 nm or increased to 150 nm, the efficiency decreases by 0.05% and 0.09%, respectively 8 . TiO 2 thin films present high refractive index that is optimal for reducing reflection losses of glass-encapsulated solar cells, low extinction factor, high thermal stability and high chemical resistance 9,10 .…”