The invention relates to a thin, nano-structured coating that provides optical light efficiency enhancement. The dried coating contains nano-structures that provide a very low haze level of less than 2 percent, and a light transmission improvement of at least 1% over the non-coated substrate. For the nano-structured coating on an acrylic substrate the transmission is greater than 93 percent, and preferably greater than 94 percent. The coatings of the invention are especially useful for optical electronic displays and photovoltaic modules.