It's kind of strange to me that when reading topics like "components of cellphone screen", people often mention an outermost anti-reflecting coating which takes advantage of destructive interference. There're few mentions for using DLC-coating as a cellphone screen outermost coating but there're indeed many researchers using DLC-coatings which are highly transparent, anti-reflective and anti-scratch for other scenarios, e.g. https://www.researchgate.net/publication/262990647_Fabrication_of_Highly_Transparent_Diamond-like_Carbon_Anti-Reflecting_Coating_for_Si_Solar_Cell_Application [Broken]. However the properties just mentioned seem perfect to be used for cellphone screens and I haven't yet found prominent usage of DLC-coating for cellphones especially for the touch-screens. Is DLC-coating popular in display industry? If not what makes it not popular given all those good properties?