51. Effects of passivation configuration and emitter surface doping concentration on polarization-type potential-induced degradation in n-type crystalline-silicon photovoltaic modules
- Author
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Yamaguchi, Seira, Aken, Bas B. Van, Stodolny, Maciej K., Löffler, Jochen, Masuda, Atsushi, Ohdaira, Keisuke, Yamaguchi, Seira, Aken, Bas B. Van, Stodolny, Maciej K., Löffler, Jochen, Masuda, Atsushi, and Ohdaira, Keisuke
- Abstract
System voltages can cause significant degradation in photovoltaic modules. Polarization-type potential-induced degradation (PID) is accompanied by decreases in the short-circuit current density and the open-circuit voltage. The system voltage causes a polarization and surface charge accumulation, increasing the interface recombination. The surface passivation and the emitter doping concentration and gradient are considered to have large impacts. However, a systematic study on these effects has not yet been performed. In this paper, the effects of the front surface structure of n-type passivated emitter and rear totally diffused cell modules were investigated by accelerated PID tests. Standard cells with thin silicon dioxide/80 nm silicon nitride (SiN_x) antireflection/passivation layers, refractive index (RI) of 2.0, exhibited typical polarization-type PID. Cells with increased RI = 2.4 for the bottom 20 nm SiN_x showed no degradation at all. This may be caused by reduced charge accumulation in the SiN_x layer near the interface due to the higher electrical conductivity of the Si-rich bottom layer. Secondly, cells with both a highly distorted interface, due to nitrogen insertion in the silicon surface, and an emitter with a high surface doping concentration have excellent resistance to PID. Cells with either the highly distorted interface or the higher emitter-surface doping concentration show no to minor improved resistance to PID. These findings improve the understanding of the effects of the front surface structure of cells on the polarization-type PID and may contribute to the implementation of these measures to reduce PID., identifier:https://dspace.jaist.ac.jp/dspace/handle/10119/18204
- Published
- 2021