Exciton-relaxation dynamics in lead halides

TL;DR

This paper reviews recent studies on exciton relaxation in lead halide crystals, highlighting spontaneous exciton dissociation, self-trapping of charge carriers, and the phonon-mediated electron-hole separation process.

Contribution

It provides a comprehensive overview of exciton relaxation mechanisms in lead halides, including experimental insights into luminescence and electron-spin-resonance findings.

Findings

Excitons in lead bromide spontaneously dissociate.

Electrons and holes become self-trapped individually.

Electron-hole separation is driven by acoustic phonons.

Abstract

We survey recent comprehensive studies of exciton relaxation in the crystals of lead halides. The luminescence and electron-spin-resonance studies have revealed that excitons in lead bromide spontaneously dissociate and both electrons and holes get self-trapped individually. Similar relaxation has been also clarified in lead chloride. The electron-hole separation is ascribed to repulsive correlation via acoustic phonons. Besides, on the basis of the temperature profiles of self-trapped states, we discuss the origin of luminescence components which are mainly induced under one-photon excitation into the exciton band in lead fluoride, lead chloride, and lead bromide.