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Microstructural Analysis of Local Silicon Corrosion of Bifacial Solar Cells as Root Cause of Potential‐Induced Degradation at the Rear Side
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 (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900334
Subject(s) - materials science , degradation (telecommunications) , corrosion , silicon , cathodic protection , impurity , common emitter , stacking , solar cell , crystalline silicon , optoelectronics , composite material , metallurgy , electrical engineering , chemistry , electrode , electrochemistry , engineering , organic chemistry
Bifacial passivated emitter and rear cells (PERC+) can suffer from potential‐induced degradation (PID) of the rear side. Rear‐side PID tests of industrial solar cells lead to more than 12% power degradation that is not recoverable under illumination or dark storage. A microstructural root‐cause analysis of the rear side reveals localized spots with increased carrier recombination as the origin of the power losses. Morphology and defect distribution depend on the temperature (60 and 85 °C) applied for PID acceleration. Individual defects are analyzed at the atomic level, revealing a corrosion of the silicon bulk at the Si/AlO x interface. A laterally extending Na accumulation at the interface and an increased concentration of further impurities are observed together with large stacking fault defects. The formation of the defects will be discussed within a simple model for a cathodic corrosion of Si and the impact of interfacial contaminations during solar cell processing.