First principles and experimental study of the electronic structure and phase stability of bulk thallium bromide

Abstract

We apply state-of-art first principle calculations to study the polymorphism and electronic structure of three previously reported phases of TlBr. The calculated band structures of NaCl-structure phase and orthorhombic-structure phase have different features than that of commonly observed CsCl-structure phase. We further interpret photoluminescence spectra based on our calculations. Several peaks close to calculated band gap values of the NaCl-structure phase and the orthorhombic-structure phase are found in unpolished TlBr samples.

Colloidal thallium halide nanocrystals with reasonable luminescence, carrier mobility and diffusion length

“…The powder XRD pattern of the TlBr NCs, which is displayed in Fig. 4b , shows a cubic phase, similar to bulk 43 TlBr, at room temperature. The inset in Fig.…”

Temperature dependence of the indirect bandgap in thallium bromide from cathodoluminescence spectroscopy

“…Luminescence emission around 3.0 eV was observed by Grabner 14 followed by reports of the indirect edge emission and absorption by Shimizu et al 4 The peak at $2.45 eV has been observed in a number of photoluminescence (PL) studies, with its origin suggested to be associated with a wide range of possible defects. 3 CL spectra were taken as a function of temperature over the range from 5 K to 295 K. Figure 2 shows the shift in the peak position for the indirect-gap related transition. The peak intensities have been normalized for comparison.…”

“…As a result of that interest, there has been additional recent work on fundamental materials properties, including studies of ionic conductivity, 6 phase stability, 3 and transport behavior. 7,8 In this work, we present variable temperature cathodoluminescence (CL) studies that provide information on the temperature dependent luminescence associated with both the indirect and direct bandgaps over the range from 5 to 300 K. The experimental results have been used to determine fitting parameters for three of the most popular semiempirical expressions for the temperature dependence of the lowest energy, indirect bandgap.…”

Transient Absorption Spectroscopy of TlBr Crystals Using Pulsed Electron Beams

“…TlBr is an indirect-gap semiconductor with direct and indirect gap energies of approximately 3.0 and 2.7 eV, respectively. (1)(2)(3)(4)(5) Owing to the high atomic numbers of its constituent elements (Tl: 81, Br: 35) and the consequent high interaction probability with high-energy photons such as X-rays and gamma rays, TlBr has long been a candidate material for semiconductor detectors of ionizing radiations. (6) Its relatively high band-gap energy is also favorable for use at room temperature.…”