Date of Graduation

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor

Simon Ang

Committee Member

Zhengrong Tian

Second Committee Member

Roy McCann

Third Committee Member

Silke Spiesshoefer

Keywords

Anti-reflective, Ethylene-vinyl Acetate, Hydrophobic, Solar Cell Packaging

Abstract

In this research, nanomaterial-based packaging materials for photovoltaic (PV) panels are investigated. A hydrophobic/anti-reflective surface coating which not only repels water from the top glass of a PV panel but at the same time reduces its light reflectance is investigated. COMSOL simulation results indicate that taller ellipsoid rod (aspect ratio = 5) reflects less light than shorter rod (aspect ratio = 0.5) in the desired spectrum for solar energy harvest from 400nm-700nm. The addition of a polymer layer on these ellipsoid rods broadens the light incident angle from 23° to 34°, from which light can be efficiently absorbed. Based on optical simulation results and surface wetting mechanics, the design of a combined anti-reflective and hydrophobic surface for PV panel is investigated. Deep reactive-ion and wet etching are used to fabricate a unique ellipsoid-shaped silicon stamp on a silicon wafer. The nano-imprinting process yields a super hydrophobic silicone coating on glass that can improve light transmittance by 1.5% with a water contact angle larger than 150°. The light transmittance of nano silica coating with a surface assembled monolayer of 1H,1H,2H,2H-Perfluorododecyltrichlorosilane prepared from a sol-gel growth is 3% higher (400nm-700nm) than that for a bare glass slide. This coating passed the MIL-STD-810G felt abrasion test, 100 cycles of temperature cycling test (-45°C-120°C), heat endurance test (200°C for 500 hours), and UV test (2.7mW/cm2 UVA radiation for 1000 hours).

The second PV packaging material investigated is the nano-particle embedded EVA encapsulation. To block the migration of harmful free radicals that cut the co-polymer network into smaller molecules by chemical reaction in EVA, nano silica particle or functionalized nano diamond particles are embedded into EVA sheets. A difference of 1% light transmittance between pristine EVA sheet and nano particle embedded EVA sheet indicates that the nano particles slow down the degradation of EVA after 2.7 mW/cm2 UVA radiation for 2 months. The embedded EVA sheet exhibits better adhesion strength on glass surface indicated by a conventional tape peeling test.

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