High Transmittance Superhydrophobic Coatings with Durable Self-Cleaning Properties

Michele Ferrari,Francesca Cirisano,Justine Vernet,Paolo Piccardo

doi:10.3390/coatings11050493

Abstract

One of the most important factors determining a significant reduction in optical devices’ efficiency is the accumulation of soiling substances such as dust, which, especially in solar power plants, implies higher costs and materials ageing. The use of superhydrophobic (SH) coatings, water contact angle (CA) greater than 150°, represents a suitable solution to improve the self-cleaning action while at the same time providing high transmittance for energy conversion. A mixed organic–inorganic SH coating with surface roughness below 100 nm was prepared by an easily scalable spray method and employed, allowing us to modulate the covered area and transparency. The coating has been also investigated while simulating pollution agents like acid rain, harsh environments, and the impact of continuous water droplets and dust particles with different physicochemical properties. The spray coating method allows us to obtain a modulated SH and self-cleaning surface showing CA > 170°, high transmittance in UV-Vis range and the ability to completely restore its initial properties in terms of wettability and transmittance after durability and soiling tests.

Highlights

Among those devices requiring a stable and linear response to light absorption over time, optical sensors, solar modules and greenhouse panes, to name but a few, are subject to numerous factors reducing their performance
The spray coating method allows us to obtain a modulated SH and self-cleaning surface showing contact angle (CA) > 170◦, high transmittance in UV-Vis range and the ability to completely restore its initial properties in terms of wettability and transmittance after durability and soiling tests
One of the key features affecting the lifetime of a solar module is the ageing of glass cover transparency, with a decrease in its transmittance especially considering its exposure and the action of environmental agents determining a significant decrease in electrical production [2,8]

Summary

Introduction

Among those devices requiring a stable and linear response to light absorption over time, optical sensors, solar modules and greenhouse panes, to name but a few, are subject to numerous factors reducing their performance. Pollution (e.g., dust in urban spaces and sands in the desert or marine environments) accumulate on the module’s surface with consequent and consistent loss of the incident light by reflection, and by dispersion or absorption [9]. Acid rain represents a pollution agent degrading materials exposed in the environment [13,14] which could be a contributing factor in the partial loss of the mechanical and structural properties [15] of the modules

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Results