Multilayer Antireflection Coatings for Cover Glass on Silicon Solar Modules

Abstract

The cover glass on solar modules provides protection for the underlying solar cells but also leads to two forms of power loss: reflection losses and soiling losses. In this work we report on the design of a broadband multilayer anti-reflection (MAR) coating designed for use with silicon modules and its advantages over commercial porous SiO2 sol-gel coatings. The six-layer anti-reflection coating comprising SiO2 and ZrO2 has then been deposited on glass using high-rate pulsed DC magnetron sputtering. The reflection losses are reduced by 2.4% absolute compared to uncoated glass, whereas commercial SiO2 coatings reduce reflection by 2.2%. The increased light reaching the solar cell improves the short-circuit current density (Jsc) and spectral response, increasing the conversion efficiency from 17.1% to 17.5%, a relative increase of 2.34%. The coating is environmentally robust and abrasion resistant, whereas porous SiO2 AR coatings are susceptible to abrasion damage and water ingress. The sputtering process used to fabricate the MAR coating is used for high throughput applications by most major glass manufacturers. We also explore the addition of a thin hydrophobic layer of refractive index n=1.35 to the outer surface of the MAR coating. Addition of the hydrophobic layer increases the water contact angle of the MAR coating from 7 • to 114 • , with a significant increase in anti-soiling properties without compromising AR performance. MAR coatings offer improved light transmission and improved durability over commercial porous SiO2 sol-gel AR coatings.

A Broadband Multilayer Antireflection Coating for Thin Film CdSeTe/CdTe Solar Cells

“…The transmission and reflection coefficients for thin film stacks can be calculated, if the refractive index (n) and extinction coefficient (k) of the thin film materials are known, and this provides the basis for the modelled reflectance curves shown in this work. This modelling approach has been used in previous work [14], [17] for the development of MAR coatings, and also in other studies focused on the optimisation of various layers in a PV device [23].…”

“…The use of fully dense layers gives advantages such as higher abrasion resistance and protection against moisture ingress. MAR coatings have previously been designed for silicon, CdTe, and other thin film PV technologies giving relative improvements in J sc as high as 3.8% [14]- [17].…”

Facile Synthesis of ZrO2–SiO2 Antireflective Films with Good Mechanical Performances for Perovskite Solar Cells

“…Additionally, some organic materials with −CH 3 groups were also added into a SiO 2 precursor sol to modify the structure of SiO 2 films, − changing the physical connection into chemical bond links among SiO 2 particles and thus improving the mechanical performance of the film. Furthermore, multilayer antireflection (MAR) coatings have been reported, which achieved good reduce-reflection effects over an extended wavelength range. − Law et al reported a six-layer AR design and materials used for each coating layer and their respective thicknesses not the scale . However, there is no doubt that selection of materials and designs of thicknesses for multilayer films would increase the complexity of the preparation process of AR coatings.…”

“…Zirconium dioxide (ZrO 2 ) has amazing properties such as wide band gap, thermal stability, and high refractive index. , Moreover, ZrO 2 is a potentially modified material with excellent mechanical performances, which can promote anti-corrosion ability through enhancing thermal stability and enlarging surface area . In this work, a ZrO 2 –SiO 2 composite film as an antireflection layer with enhanced pencil hardness and higher transmittance gain was successfully prepared by a facile sol–gel method, comparing with the pure SiO 2 film synthesized with the same alkali-catalyzed method.…”

“…29−31 Law et al reported a six-layer AR design and materials used for each coating layer and their respective thicknesses not the scale. 32 However, there is no doubt that selection of materials and designs of thicknesses for multilayer films would increase the complexity of the preparation process of AR coatings. Hence, modifying the monolayer SiO 2 AR coating is a relatively simple method.…”