FTIR Investigation of EVA Chemical Bonding Environment and its Impact on Debond Energy

Laura Spinella, Nicholas Bosco

Research output: Contribution to journalArticlepeer-review

12 Scopus Citations

Abstract

The chemical makeup of ethylene vinyl acetate (EVA) interfaces in photovoltaic (PV) modules is probed via Fourier-transform infrared spectroscopy (FTIR) to determine the impact of the EVA formulation on the adhesion degradation. EVA samples laminated with glass particles are used to demonstrate the effect of damp heat exposure on the glass-EVA interface, showing that increasing silane content increases chemical stability. Delamination interfaces created in one cell modules demonstrate a high correlation between the siloxane bonding at the silicon cell-EVA interface and the debond energy. A significant decrease in debond energy after UV exposure is also shown to be due in part to decreasing siloxane bond density at the interface. However, FTIR results indicated contributions to the adhesion beyond the chemical interface, and a basic tensile test indicates increasing bulk mechanical properties with increasing silane. These results demonstrate the importance of the EVA formulation on its adhesion performance and long-term reliability. Furthermore, it is shown that FTIR is a capable technique for assessing and quantifying chemical mechanisms within PV modules. These results can then be used to more effectively model module lifetimes and to better design polymer systems for PV modules.

Original languageAmerican English
Article number8680756
Pages (from-to)790-795
Number of pages6
JournalIEEE Journal of Photovoltaics
Volume9
Issue number3
DOIs
StatePublished - May 2019

Bibliographical note

Publisher Copyright:
© 2019 IEEE.

NREL Publication Number

  • NREL/JA-5K00-72531

Keywords

  • Adhesion
  • degradation
  • delamination
  • encapsulant
  • Fourier-transform infrared spectroscopy (FTIR) spectroscopy
  • reliability

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