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Title: PVDF-based backsheet cracking: Mapping in situ phase evolution by X-ray scattering

Journal Article · · Solar Energy Materials and Solar Cells
ORCiD logo [1];  [2];  [1];  [1];  [2];  [2]; ORCiD logo [2];  [3];  [3]; ORCiD logo [2]; ORCiD logo [1]
  1. National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States)
  2. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  3. Du Pont de Nemours (E.I.) and Co., Wilmington, DE (United States)
+ Show Author Affiliations

One of the most common polymers used in commercial photovoltaic backsheets is polyvinylidene fluoride (PVDF). However, recent reports have shown the potential for PVDF-based backsheets to crack and fail prematurely. Previous work has suggested that polymer phase changes play a role in the failure mechanism. Here, in situ wide-angle X-ray scattering maps are used to show that α- to β-phase transformations occur at crack tips in aged PVDF-based backsheets under stretching. Substantial β-phase formation is shown to be associated with strain hardening. In addition, our work demonstrates that β-phase formation is not required for crack growth and only occurs at crack tips when plastic deformation of the PVDF polymer has occurred. In conclusion, the anisotropy in the strength of aged PVDF-based backsheets is linked to the lack of β-phase formation when strain is applied to aged backsheets in the transverse direction.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office; USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC36-08GO28308; AC02-76SF00515
OSTI ID:
2525872
Report Number(s):
NREL/JA--5K00-90258; MainId:92036; UUID:72fdb852-e416-4471-be77-891b7c62a943; MainAdminId:76221
Journal Information:
Solar Energy Materials and Solar Cells, Journal Name: Solar Energy Materials and Solar Cells Vol. 282; ISSN 0927-0248
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

14 SOLAR ENERGY
Polymer phase
Polyvinylidene fluoride
Solar panel backsheets
Wide-angle X-ray scattering