Embodiments of a high-permittivity, low-leakage energy storage device, such as a capacitor, and methods of making the energy storage device are disclosed. The disclosed device includes electrically conductive first and second electrodes, and a sterically constrained dielectric film disposed between the first and second electrodes. The sterically constrained dielectric film comprises a plurality of polymeric molecules, and at least some of the polymeric molecules are bound to the first electrode. The disclosed device may include an insulative layer between the first electrode and the dielectric film and/or between the second electrode and the dielectric film.