Self-trapped states and the related luminescence in PbCl$_2$ crystals

TL;DR

This study investigates the localized electron-hole pairs and their luminescence in PbCl₂ crystals across a wide temperature range, revealing temperature-dependent self-trapping behaviors and their relation to specific photoluminescence bands.

Contribution

It provides a detailed analysis of self-trapped states and their thermal stability in PbCl₂, elucidating the connection between localized states and luminescence.

Findings

Holes localize on Pb²⁺ ions forming Pb³⁺ centers below 70 K.

Electrons localize on two Pb²⁺ ions forming Pb₂³⁺ centers above 50 K.

The 2.50 eV PL band is linked to self-trapped holes.

Abstract

We have comprehensively investigated localized states of photoinduced electron-hole pairs with electron-spin-resonance technique and photoluminescence (PL) in a wide temperature range of 5-200 K. At low temperatures below 70 K, holes localize on Pb$^{2+}$ ions and form self-trapping hole centers of Pb$^{3+}$. The holes transfer to other trapping centers above 70 K. On the other hand, electrons localize on two Pb$^{2+}$ ions at higher than 50 K and form self-trapping electron centers of Pb$_2$$^{3+}$. From the thermal stability of the localized states and PL, we clarify that blue-green PL band at 2.50 eV is closely related to the self-trapped holes.