A novel wet coating method using small amounts of solution on large flat substrates

- A novel coating machine is invented for coating large flat substrates.
- A very small amount of coating solution (<20 ml/m2) for the coating process.
- One-sided and double-sided homogeneous thin films could be fabricated.
- Anti-reflective coatings with the average transmittance up to 94.7% in visible wavelengths.

Coating on large surfaces is a critical issue in both academic studies and industrial production. This work proposes a novel method of coating a large flat substrate (50 × 100 cm2) via a wet chemical process using a very small amount (20 ml) of coating solution. The sol material consisted of surface-modified silicon dioxide (SiO2) nanoparticles (10-30 nm), which have the optimal antireflective (AR) function in the visible spectral range for thin films with a thickness ranging from 110 to 120 nm.Ellipsometry results demonstrate a homogeneous thickness of the AR coating on glass (109.4 ± 2.7 nm). A deviation of less than 3% over a large coated surface was observed. Crack-free coatings with homogeneous morphology on the surface of the coatings were observed using scanning electron microscopy. The AR effect was confirmed with UV-vis measurements, with an average transmittance of 91.1% and 94.7%, respectively, in visible wavelengths for the one-sided and double-sided AR coatings (in comparison to 88% for uncoated glass).

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