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Local Corrosion of Silicon as Root Cause for Potential‐Induced Degradation at the Rear Side of Bifacial PERC Solar Cells
Author(s) -
Sporleder Kai,
Naumann Volker,
Bauer Jan,
Richter Susanne,
Hähnel Angelika,
Großer Stephan,
Turek Marko,
Hagendorf Christian
Publication year - 2019
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201900163
Subject(s) - passivation , materials science , transmission electron microscopy , degradation (telecommunications) , silicon , stack (abstract data type) , corrosion , layer (electronics) , focused ion beam , electron beam induced current , deep level transient spectroscopy , scanning electron microscope , impurity , composite material , optoelectronics , ion , electrical engineering , chemistry , nanotechnology , organic chemistry , computer science , programming language , engineering
Industrial bifacial PERC solar cells are exposed to a high‐voltage stress at the rear side. The tested cells show a potential‐induced degradation (PID) in V oc and I sc . From a front side current–voltage measurement, a power loss of about 12% rel is observed, however, without a significant change in the fill factor. The degradation is traced back to micron‐sized hole‐shaped damages of the rear surface, which correlate with localized regions of increased recombination. A focused ion beam (FIB) cross‐section through a hole‐shaped damage is performed for subsequent transmission electron microscopy (TEM) and energy‐dispersive X‐ray spectroscopy (EDXS). EDXS shows an accumulation of Na, K, and Ca impurities in the cavity. Thus, it is assumed that corrosion of the Si surface occurs beneath the AlO x /SiN y passivation layer stack and is accompanied by the formation of a SiO 2 layer.