Excitonic States of Pb Ion Clusters in Pb_1-xCd_xI₂Solid Solutions Studied with Time-Resolved Emission Spectra

Abstract

Emission and excitation spectra of the luminescence in Pb 1- x Cd x I 2 solid solutions have been investigated in the range of x between 0.5 and 0.8. Emission band observed near the absorption edge is attributed to the luminescence associated with Pb ion clusters dispersed in CdI 2 matrix. Time-resolved measurements of the emission spectra reveal that the emission band consists of singlet and triplet components. The energy split between the singlet and triplet states is found to increase with decrease in the cluster size. The result is discussed in relation to an exciton Bohr radius.