Centers of near-infrared luminescence in bismuth-doped TlCl and CsI crystals

TL;DR

This study uses first-principles calculations to identify the specific bismuth-related centers responsible for near-infrared luminescence in TlCl and CsI crystals, aligning theoretical models with experimental observations.

Contribution

It provides a comparative analysis of bismuth centers in TlCl and CsI, identifying the specific defects responsible for IR luminescence through computational modeling.

Findings

Bi--Vac(Cl) centers cause IR luminescence in TlCl:Bi.

Bi^+ ions and Bi_2^+ dimers cause IR luminescence in CsI:Bi.

Theoretical results agree with experimental data.

Abstract

A comparative first-principles study of possible bismuth-related centers in TlCl and CsI crystals is performed and the results of computer modeling are compared with the experimental data. The calculated spectral properties of the bismuth centers suggest that the IR luminescence observed in TlCl:Bi is most likely caused by Bi--Vac(Cl) centers (Bi^+ ion in thallium site and a negatively charged chlorine vacancy in the nearest anion site). On the contrary, Bi^+ substitutional ions and Bi_2^+ dimers are most likely responsible for the IR luminescence observed in CsI:Bi.