Durable Antireflective Antifog Al Micro-Nano Structure on glass by Laser Ablation

What is it about?

Fogging poses a significant challenge, occasionally jeopardizing life safety in automotive and surgical fields. The maintenance of high efficiency in photovoltaic systems necessitates regular cleaning, consuming millions of tons of water annually, rendering it financially burdensome in arid regions. The implementation of glass antireflection is a necessary strategy for enhancing photovoltaic efficiency. Therefore, self-cleaning, antifog and antireflective properties have attracted wide attention. A hierarchical micron-nano structure was fabricated by laser marker fast ablation of Al coated soda lime glass in air. The composition, structure, morphology, transparency, and anti-fog performance of the structured samples were measured and analyzed. The influence of Al coating thickness and laser scanning speed on the resulting surface properties was investigated. The structured surface exhibited a distinct hillock-hollow micro-structure, with widely distributed Al-based nanoparticles covering the entire surface. Consequently, the treated samples demonstrated a water contact angle of 0°, siginfing superhydrophilicity, and exhibited outstanding and durable antifogging properties for over 150 days. Even after 540 days of storage in the laboratory, a noticeable antifog effect persisted for the treated sample compared to the reference, which had degraded substantially. Notably, achieving 0-degree superhydrophilicity took within a mere 1 second for the structured surface, which also showed outstanding antifouling and self-cleaning attributes. Moreover, the treated glass exhibited a broadband transmission enhancement of 2% in the range of 400-1100 nm compared to the control glass. It is important to highlight that the combination of durable superhydrophilic antifog performance, self-cleaning attribute, and broadband transmission enhancement has not been reported previously for laser-ablated surfaces. This technique exhibits significant potential for wide-ranging applications across multiple fields.

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Why is it important?

The photovoltaic cover glass and air interface accounts for ~4% absolute energy loss due to reflection. The cover glass exposed to severe outdoor environment is subject to fog, dust, contamination, which blocked or scattered light causing further losses. Regular cleaning maintenance increased cost and might cause damage to the glass[1]. Superhydrophilic surfaces inherently feature self-cleaning. Fogging on glass is a common phenomenon. The over-saturated vapor in the air will form small water droplets when contacting with glass[7], which will reflect and scatter light, and adversely affect the use of optical instruments such as glasses[8,9]and lenses[10]. There are two antifogging methods. To simutaneously achieve self-cleaning antifog and antireflection is much desirable for many applications.

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