Depth profiling of mechanical degradation of PV backsheets after UV exposure

Xiaohong Gu; Peter J. Krommenhoek; Chiao-Chi Lin; Li-Chieh Yu; Tinh Nguyen; Stephanie S. Watson

doi:10.1117/12.2187171

23 September 2015 Depth profiling of mechanical degradation of PV backsheets after UV exposure

Xiaohong Gu, Peter J. Krommenhoek, Chiao-Chi Lin, Li-Chieh Yu, Tinh Nguyen, Stephanie S. Watson

Proceedings Volume 9563, Reliability of Photovoltaic Cells, Modules, Components, and Systems VIII; 956305 (2015) https://doi.org/10.1117/12.2187171
Event: SPIE Optics + Photonics for Sustainable Energy, 2015, San Diego, California, United States

Abstract

Polymeric multilayer backsheets protect the photovoltaic modules from damage of moisture and ultraviolet (UV) while providing electrical insulation. Due to the multilayer structures, the properties of the inner layers of the backsheets, including their interfaces, during weathering are not well known. In this study, a commercial type of PPE (polyethylene terephthalate (PET)/PET/ethylene vinyl acetate (EVA)) backsheet films was selected as a model system for a depth profiling study of mechanical properties of a backsheet film during UV exposure. The NIST SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) was used for the accelerated laboratory exposure of the materials with UV at 85°C and two relative humidities (RH) of 5 % (dry) and 60 % (humid). Cryomicrotomy was used to obtain cross-sectional PPE samples. Mechanical depth profiling of the cross-sections of aged and unaged samples was conducted by nanoindentation, and a peak-force based quantitative nanomechanical atomic force microscopy (QNM-AFM) mapping techniquewas used to investigate the microstructure and adhesion properties of the adhesive tie layers. The nanoindentation results show the stiffening of the elastic modulus in the PET outer and pigmented EVA layers. From QNM-AFM, the microstructures and adhesion properties of the adhesive layers between PET outer and core layers and between PET core and EVA inner layers are revealed and found to degrade significantly after aging under humidity environment. The results from mechanical depth profiling of the PPE backsheet are further related to the previous chemical depth profiling of the same material, providing new insights into the effects of accelerated UV and humidity on the degradation of multilayer backsheet.

Conference Presentation

Citation Download Citation

Xiaohong Gu, Peter J. Krommenhoek, Chiao-Chi Lin, Li-Chieh Yu, Tinh Nguyen, and Stephanie S. Watson "Depth profiling of mechanical degradation of PV backsheets after UV exposure", Proc. SPIE 9563, Reliability of Photovoltaic Cells, Modules, Components, and Systems VIII, 956305 (23 September 2015); https://doi.org/10.1117/12.2187171

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available