Effects of SiNx refractive index and SiO2 thickness on polarization‐type potential‐induced degradation in front‐emitter n‐type crystalline‐silicon photovoltaic cell modules. Issue 7 (31st March 2022)

• Record Type: Journal Article
• Authors: Yamaguchi, Seira; Nakamura, Kyotaro; Semba, Taeko; Ohdaira, Keisuke; Marumoto, Kazuhiro; Ohshita, Yoshio; Masuda, Atsushi
• Is Part Of: Energy science & engineering. Volume 10:Issue 7(2022)
• Page Start: 2268
• Page End: 2275
• Publication Date: 2022-03-31
• Subjects: acceleration test -- n‐type crystalline‐silicon solar cell -- passivated emitter and rear totally diffused cell -- photovoltaic module -- polarization‐type potential‐induced degradation -- reliability; Energy industries -- Periodicals; Energy development -- Periodicals; Power resources -- Periodicals; 621.042
• DOI: 10.1002/ese3.1135
• Languages: English
• ISSNs: 2050-0505

Abstract

Abstract: This study investigated how the SiN x refractive index (RI) and SiO2 thickness, d ox, of stacked SiN x /SiO2 passivation layers of the front p + emitters of n‐type crystalline‐silicon (c‐Si) photovoltaic (PV) cells affect their polarization‐type potential‐induced degradation (PID) behaviors. We prepared six n‐type c‐Si PV cells with an RI of 2.0 or 2.2 and with d ox of 9, 2, or 1 nm. Then PV modules fabricated from the cells were subjected to PID tests during which a bias of −1000 V was applied to cells with respect to the front cover glass surface. For d ox of 9 or 2 nm, rapid polarization‐type PID was observed, irrespective of the RI. However, for d ox of 1 nm, the RI markedly affected the degradation behavior, and cells with an RI of 2.2 showed no degradation. These findings are attributable to carrier transport between the high RI (Si‐rich) SiN x and the c‐Si substrates, which can readily occur only when the SiO2 layer is sufficiently thin for electrons to tunnel through the SiO2 layer. These results are important for elucidating polarization‐type PID mechanisms and for developing preventive measures against polarization‐type PID. Abstract : We investigated how the SiN x refractive index (RI) and SiO2 thickness, d ox, of SiN x /SiO2 layers of n‐type crystalline‐silicon photovoltaic cells affect polarization‐type potential‐induced degradation. For d ox greater than 2 nm, rapid degradation was observed irrespective of the RI. However, for d ox of 1 nm, the RI strongly affected degradation, and 2.2‐RI cells showed no degradation.