Various embodiments include an interferometric modulator device configured to provide improved saturation. In some embodiments, saturation is improved by optically matching the impedance of two materials with different refractive indices using a multilayer having a refractive index gradient. In various embodiments, the thickness one or more of the layers in the multilayer are selected to provide increased saturation. Accordingly, in various embodiments the multilayer having a refractive index gradient helps to narrow the resonance of a pixel such that the band of wavelengths that are reflected from the pixel is smaller. In turn, a device including a combination of red, green and blue pixels may expand the spectrum of colors that are reflected by the device in operation. Additionally, there may be better contrast between whites and blacks, as darker blacks with less hue are produced.