Edgehog Anti-reflection

TandemLaunch/Univ. of Toronto

Dr. Nasim Sahraei Khanghah

Co-founder, Edgehog

Most optoelectronic devices such as consumer displays, require glass or plastic covers for protection against environmental stress. These protecting layers create optical reflections which can significantly reduce the device performance. Currently, the most common approach to minimize these reflections is to deposit optically interfering thin films (antireflection (AR) coating). However, the optical properties of these thin-film coatings are strongly dependent on the wavelength, angle and polarization of the incident light, which greatly limits their antireflection performance. A more powerful solution to reduce the reflectance is to eliminate the discontinuity at the interface altogether by gradually varying the refractive index between the two materials. Creating an effective refractive index with the desired spatial profile can be accomplished by appropriately texturing the surface at a scale smaller than the wavelength of light. Edgehog’s solution, bio-inspired antireflective nanotextures, is a highly scalable approach to drastically reduce reflections on various substrates, over the entire visible and near-IR spectrum, and even at large angles of incidence. The antireflection effect derives from the gentle gradience of refractive index from air to substrate, which enables 99.9% transmittance on glass. The nanostructure lateral dimension is less than 100 nm, so a broad and flat antireflection effect is observed throughout the visible spectrum (reflectance < 0.1%). This makes Edgehog’s technology exceptionally suitable for displays. The low reflectance prevents the deterioration of contrast ratio typically observed under bright conditions. As such, the color of the reflectance stays neutral regardless of the viewing angle. The surface is also superhydrophobic and self-cleaning.

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