A method for depositing an iodine-containing film on a substrate material comprises: exposing the substrate material to a vapor of a film-forming composition comprising an iodine-containing precursor having a formula of CaHxIyFz, wherein a=1-10, x≥0, y≥1, z≥0, x+y+z=a, 2a or 2a+2; provided that when a=1, x=2 and z=0, y is not equal to 2, and depositing the iodine-containing film formed by the iodine-containing precursor on the substrate material through a vapor deposition method. The method further comprises exposing the substrate material to a vapor of a co-reactant nitrogen-containing molecule having a general formula CxHyFzNH, where x=1-6, y=0-13, z=0-13, and a=1-2 or CxHyFzN—R1, where x=1-6, y=0-13, z=0-13, and R1 is a C1-C5 hydrocarbon.