The figure below compares the light spectra for an LCD that has a Backlight with Quantum Dots with an LCD that has a White LED Backlight.

Note the sharp and narrow peaks for the Kindle Fire HDX 7 that has a Backlight with Quantum Dots, which produces saturated colors that are quite similar to those produced by OLEDs. The very broad spectrum for the iPad mini Retina Display that has a Backlight with White LEDs, produces much less saturated colors.