Thermal quenching of chromium photoluminescence in ordered perovskites. I. Temperature dependence of spectra and lifetimes

The temperature dependence of chromium photoluminescence spectra and lifetimes have been measured in ordered perovskite (${\mathrm{Cs}}_2$ ${\mathrm{NaYCl}}_6$, ${\mathrm{K}}_2$ ${\mathrm{NaScF}}_6$, and ${\mathrm{K}}_2$ ${\mathrm{NaGaF}}_6$) host crystals. Analysis of lifetime data yields thermal-quenching activation energies ΔE of 4250, 7270, and 9240 ${\mathrm{cm}}^{\mathrm{-}1}$, respectively. The Mott theory, applied to a single-configuration-coordinate, linear-coupling model with parameters inferred from emission spectra, fails by 20 orders of magnitude to explain the observed radiationless-transition rate.