The optical properties and surface morphologies of sputtering films both without and with use of the ion-assisted deposition (IAD) technique are investigated and compared. Optimal antireflection (AR) coating films with SiO2/Nb2O5 layers, which are grown at 80 degrees C with a 15 cm distance between target and substrate, 55 SCCM oxygen flow (SCCM denotes cubic centimeters per minute at STP), and 1250 W magnetron sputtering power with use of the IAD technique, are used to study the optical performance. By using an atomic force microscope to investigate the surface of the sputtered Nb2O5 films, we find that the films' roughness is 0.185 nm. On a flexible hardness polycarbonate (HPC) substrate with the multilayer AR films, the peak transmittances measured in the visible range are 95.89% and 93.40%, respectively, for coatings with and without use of the IAD sputtering technology. These results are better than those measured with a bare HPC substrate (91.25%) and are well above the commercial liquid-crystal display standard (90%) and flexible application.