Date of Graduation

5-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Electrical Engineering

Advisor/Mentor

Ang, Simon S.

Committee Member

Tian, Z. Ryan

Second Committee Member

McCann, Roy A.

Third Committee Member

Spiesshoefer, Silke A.

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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