A facile route to create surface porous polymer films via phase separation for antireflection applications

A facile route was developed to create surface porous polystyrene/poly(vinylpyrrolidone) (PS/PVP) films, via phase separation in a dip-coating process, for antireflection applications. The film thickness, pore size, and pore depth of the product films can be effectively adjusted with the concentration of the PS/PVP (volume ratio of 7:3) solution and withdrawal speed. At an optimal concentration of 0.6 wt % and withdrawal speed of 19 cm/min, the product films had an average thickness of 125 nm, a pore size of 156 nm, and a pore depth of 20 nm, giving a percent transmittance increase of 3-4% over the bare glass. Further removal of the PVP phase, which was concentrated at the pore bottom, with water etching deepened the pore depth to 37 nm, thus boosting the percent transmittance for another 0.5%.