NOVELTY - The method comprises depositing a polyvinylpyrrolidone (PVP) solution on a surface of a substrate to form a PVP film, and depositing a silica solution on the formed PVP film on the substrate to form a silica film for forming a stack structure. The PVP solution has a concentration of 1-20 wt.%. The PVP film has a thickness of 5-300 nm. The silica film has a thickness of 5-300 nm. The PVP film dissolves in the silica solution of the silica film as the silica film is formed on the PVP film. Each of the depositing steps is performed by a dip coating-, spray coating- and/or roll coating process.    USE - The method is useful for forming an antireflective coating on a substrate, where the antireflective coating is useful in a solar panel and a photovoltaic device (all claimed).    ADVANTAGE - The method is capable of uniformly forming the coating with high optical transmittance and antireflective performance thus enhancing efficiencies and power output of the photovoltaic device.    DETAILED DESCRIPTION - The method comprises depositing a polyvinylpyrrolidone (PVP) solution on a surface of a substrate to form a PVP film, and depositing a silica solution on the formed PVP film on the substrate to form a silica film for forming a stack structure. The PVP solution has a concentration of 1-20 wt.%. The PVP film has a thickness of 5-300 nm. The silica film has a thickness of 5-300 nm. The PVP film dissolves in the silica solution of the silica film as the silica film is formed on the PVP film. Each of the depositing steps is performed by a dip coating-, spray coating- and/or roll coating process. The method further comprises drying the stack structure to form an antireflective coating on the substrate, and cleaning the substrate by ultrasonication before deposition of the PVP solution. The antireflective coating comprises silica nanoparticles (130) adhered on the surface of the substrate. The drying step is performed at a temperature of 10-1200 degrees C. The substrate is formed of a transparently dielectric material having a refractive index. The polyvinylpyrrolidone solution contains a transparent polymer having a refractive index. The refractive index of the transparent polymer is present between a refractive index of air and the refractive index of the dielectric material.    DESCRIPTION OF DRAWING(S) - The figure shows a schematically cross sectional view of an antireflective coating.    Substrate (110)    Polymer film (120)    Silica nanoparticles. (130)