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Temperature Accelerated Life Test and Failure Analysis on Upright Metamorphic Ga 0.37 In 0.63 P/Ga 0.83 In 0.17 As/Ge Triple Junction Solar Cells
Author(s) -
Orlando Vincenzo,
Lombardero Iván,
Gabás Mercedes,
Nuñez Neftali,
Vázquez Manuel,
EspinetGonzález Pilar,
Bautista Jesús,
Romero Rocio,
Algora Carlos
Publication year - 2020
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3223
Subject(s) - metamorphic rock , materials science , geology , geochemistry
A temperature accelerated life test on Upright Metamorphic Ga 0.37 In 0.63 P/Ga 0.83 In 0.17 As/Ge triple‐junction solar cells has been carried out. The acceleration has been accomplished by subjecting the solar cells to temperatures (125, 145 and 165°C) significantly higher than the nominal working temperature inside a concentrator (90°C), while the nominal photo‐current (500×) has been emulated by injecting current in darkness. The failure distributions have been fitted to an Arrhenius–Weibull model resulting in an activation energy of 1.39 eV. Accordingly, a 72 years warranty time for those solar cells for a place like Tucson (AZ, USA), was determined. After the ALT, an intense characterization campaign has been carried out in order to determine the failure origin. We have detected that temperature soak alone is enough to degrade the cell performance by increasing the leakage currents, the series resistance, and the recombination currents. When solar cells were also forward biased an increase of series resistance together with a reduction of short circuit current is detected. The failure analysis shows that: a) several metallization sub‐products concentrate in several regions of front metal grid where they poison the silver, resulting in a two times reduction of the metal sheet resistance; b) the metal/cap layer interface is greatly degraded and there is also a deterioration of the cap layer crystalline quality producing a huge increase of the specific front contact resistance, c) the decrease of short circuit current is mainly due to the GaInP top subcell degradation.