Impurity luminescence of K2ZnI4 : Sn crystals

The results of studies of the photo luminescence spectra, photo luminescenc e excitation spectra and the absolute quantum efficiency of the photolumine scence eta (q) in K2ZnI4:Sn crystal are reported for the temperature range of 77-293 K. The photoluminescence spectrum at 77 K consists of the two ban ds peaked at 1.87 eV (A(T1)) and 2.01 eV (A(T2)). A, B, C and D absorption bands of the Sn2+ centres are identified in the excitation photoluminescenc e spectra of K2ZnI4:Sn. The value of the absolute quantum efficiency of the photoluminescence at 77 K is equal to eta (q) = 0.69 +/- 0.10. The tempera ture quenching of Sn2+ centre luminescence in K2ZnI4 occurs at T approximat e to 180 K, i.e. at considerably lower temperatures than that in alkali hal ide crystals. The activation energy of the non-radiative transitions calcul ated from the temperature dependence of value eta (q) is equal to epsilon = 5.8 meV. (C) 2001 Published by Elsevier Science B.V.