Design rule for the emission linewidth of Eu2+-activated phosphors

We study from first principles the emission linewidth of Eu2+-doped LED phosphors. Based on the one-dimensional configuration coordinate model, an analysis of first principles data obtained for fifteen compounds show that, at working temperature, the linewidth of Eu2+ emission band in solids is negligibly affected by quantum effects, and can be extracted from the Franck–Condon energy shifts. For a fixed Stokes shift, the difference of Franck–Condon energy shifts in the excited and ground states is the key factor for the FWHM determination. Narrow emission Eu2+-doped LED phosphors are expected for the case with large positive value of such difference.