[georgeburdell]

The promotional document focuses on wavelength tunability but I imagine brightness at any one wavelength suffers because to emit at one wavelength requires an electron to lose the amount of energy in that photon by transitioning from a high to low energy state. Maximum brightness then corresponds to how many of these transitions are possible in a given amount of time.

Some states are not accessible at a given time (voltage can tune which states are available) but my understanding is the number of states is fixed without rearranging the atoms in the material.