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.
@article{arxiv.cond-mat/0208320,
title = {Exciton-relaxation dynamics in lead halides},
author = {Masanobu Iwanaga and Tetsusuke Hayashi},
journal= {arXiv preprint arXiv:cond-mat/0208320},
year = {2009}
}