Single-layered porous silica films on polyethylene terephthalate substrates for antireflection coatings

Single-layered porous silica films were prepared on polyethylene terephthalate (PET) substrates as antireflection coatings for efficient, large-scale flexible optoelectronic devices. Cetyltrimethylammonium bromide (CTAB)-templated synthesis was employed to form porous silica films. Without using high temperature treatment, CTAB was removed by washing in water to create a porous structure in the films. To spin-coat on PET substrates, contact angle between silica sol and PET surface was measured to optimize the molar ratio of the solution. Pore size and surface sharpness were estimated using atomic force microscope data. The average reflectance of as-prepared AR coatings on PET substrates was ≤2%.