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Proceedings Paper

Characterizing the weathering induced changes in optical performance and properties of poly(ethylene-terephthalate) via MaPd:RTS spectroscopy
Author(s): Devin A. Gordon; Lin DeNoyer; Corey W. Meyer; Noah W. Sweet; David M. Burns; Laura S. Bruckman; Roger H. French
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Paper Abstract

Poly(ethylene-terephthalate) (PET) film is widely used in photovoltaic module backsheets for its dielectric break- down strength, and in applications requiring high optical clarity for its high transmission in the visible region. However, PET degrades and loses optical clarity under exposure to ultraviolet (UV) irradiance, heat, and moisture. Stabilizers are often included in PET formulation to increase its longevity; however, even these are subject to degradation and further reduce optical clarity. To study the weathering induced changes in the optical properties in PET films, samples of a UV-stabilized grade of PET were exposed to heat, moisture, and UV irradiance as prescribed by ASTM-G154 Cycle 4 for 168 hour time intervals. UV-Vis reflection and transmission spectra were collected via Multi-Angle, Polarization-Dependent, Reflection, Transmission, and Scattering (MaPd:RTS) spectroscopy after each exposure interval. The resulting spectra were used to calculate the complex index of refraction throughout the UV-Vis spectral region via an iterative optimization process based upon the Fresnel equations. The index of refraction and extinction coefficient were found to vary throughout the UV-Vis region with time under exposure. The spectra were also used to investigate changes in light scattering behavior with increasing exposure time. The intensity of scattered light was found to increase at higher angles with time under exposure.

Paper Details

Date Published: 23 August 2017
PDF: 15 pages
Proc. SPIE 10370, Reliability of Photovoltaic Cells, Modules, Components, and Systems X, 1037005 (23 August 2017); doi: 10.1117/12.2274113
Show Author Affiliations
Devin A. Gordon, Case Western Reserve Univ. (United States)
Lin DeNoyer, Deconvolution & Entropy Consulting (United States)
Corey W. Meyer, Case Western Reserve Univ. (United States)
Noah W. Sweet, Case Western Reserve Univ. (United States)
David M. Burns, 3M Co. (United States)
Laura S. Bruckman, Case Western Reserve Univ. (United States)
Roger H. French, Case Western Reserve Univ. (United States)

Published in SPIE Proceedings Vol. 10370:
Reliability of Photovoltaic Cells, Modules, Components, and Systems X
Neelkanth G. Dhere; Keiichiro Sakurai; Michael D. Kempe, Editor(s)

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