You may soon be able to read from your smartphone even under bright sunlight, thanks to an ‘invisible glass’ developed by scientists – including those from India – that reflects almost no light. Most of today’s electronics devices are equipped with glass or plastic covers for protection against dust, moisture, and other environmental contaminants, but light reflection from these surfaces can make information displayed on the screens difficult to see. Scientists from the Indian Institute of Science Education and Research (IISER) Pune in Maharashtra and the US Center for Functional Nanomaterials (CFN) have demonstrated a method for reducing the surface reflections from glass surfaces to nearly zero by etching tiny nanoscale features into them. Whenever light abruptly enters one medium from another, a portion of the light is reflected. The nanoscale features have the effect of making the refractive index change gradually from that of air to that of glass, thereby avoiding reflections. The ultra-transparent nanotextured glass is antireflective over the entire visible and near-infrared spectrum, and across a wide range of viewing angles. Reflections are reduced so much that the glass essentially becomes invisible.
This “invisible glass” could do more than improve the user experience for consumer electronic displays. It could enhance the energy-conversion efficiency of solar cells by minimising the amount of sunlight lost to refection. It could also be a promising alternative to the damage- prone antireflective coatings conventionally used in lasers that emit powerful pulses of light, such as those applied to the manufacture of medical devices and aerospace components. “We’re excited about the possibilities,” said CFN Director Charles Black. “Not only is the performance of these nanostructured materials extremely high, but we’re also implementing ideas from nanoscience in a manner that we believe is conducive to large-scale manufacturing,” said Black, corresponding author of the study published in the journal Applied Physics Letters.
“This simple technique can be used to nanotexture almost any material with precise control over the size and shape of the nanostructures,” said Atikur Rahman, an assistant professor at IISER Pune. “The best thing is that you don’t need a separate coating layer to reduce glare, and the nanotextured surfaces outperform any coating material available today,” Rahman said.