Novel hyper-branched, dense, high-refractive-index polymers, and compositions utilizing those polymers are provided, along with methods of forming high refractive index films with those compositions. The refractive index of the material is at least about 1.8 at 400 nm. Further, it can be made into optically transparent thin films of only a couple hundred angstroms thickness to thick films of several micrometers thick, as well as into “bulk” solids. The use of a thermal acid or a photo acid generator facilitates crosslinking after the coating process.