This disclosure provides systems, methods and apparatus for storage capacitors. In one aspect, an electromechanical systems (EMS) device includes a substrate, an optical stack disposed over the substrate, a mechanical layer positioned over the optical stack, and a storage capacitor. The optical stack includes a stationary electrode and at least one dielectric layer disposed over the stationary electrode, and the storage capacitor includes a first plate, a second plate and a dielectric structure disposed between the first and second plates. The first plate includes a portion of the mechanical layer positioned over an optically non-active region of the device, and the dielectric structure of the storage capacitor includes a portion of the at least one dielectric layer of the optical stack.