Self-assembled hemispherical nanowell arrays for superhydrophobic antireflection coatings.

The present study reports an inexpensive and simple bottom-up technology for fabricating superhydrophobic antireflection coatings with highly ordered hemispherical nanowell structures, which are assembled by a scalable Langmuir-Blodgett technology. The subwavelength gratings lead to a gradual change in the effective refractive index, substantially suppressing specular reflection over the entire visible wavelength range. After surface modification with fluorinated silane, the resulting nanowell arrays exhibit superhydrophobic surface with high static water contact angle (154°) and low water contact angle hysteresis (7°). The experimental results on the wettability can be qualitatively interpreted by adopting the Cassie's dewetting model. Moreover, the effect of the nanowell shape on the antireflective and superhydrophobic properties has also been investigated in the study.