First‐principles investigation of structural, optoelectronic, and thermoelectric properties of Cs ₂ Tl(As/Sb)I ₆

Abstract

Summary In this article, we have systematically investigated the structural, electronic, optical, and thermoelectric properties of Cs2Tl(As/Sb)I6. The obtained negative formation energy along without the presence of imaginary phonon frequency confirmed the thermodynamic stability of Cs2Tl(As/Sb)I6. In addition, the new mBJ approach showed the direct band gap value of 1.10 and 1.33 eV for Cs2TlAsI6 and Cs2TlSbI6, respectively. Furthermore, the dispersed direct band nature of Cs2Tl(As/Sb)I6 leads to their outshining optical properties such as higher‐order (105 cm−1) absorption coefficient, appreciable optical conductivity, and low reflectivity. Moreover, the higher figure of merit values of Cs2Tl(As/Sb)I6 are resulted from their ultra‐low thermal conductivity and high electrical conductivity. Thus, Cs2Tl(As/Sb)I6 are predicted to be potential photovoltaic and thermoelectric materials.

Lead-free all-inorganic halide double perovskite materials for optoelectronic applications: progress, performance and design

“…43 Fig. 2 presents a summary of the formability of recently reported LFAIHDPs 21,32,34,38,[44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] in a t eff -m eff map, where the existing double perovskites generally satisfy these conditions. For quantitative prediction, firstprinciples calculations based on density functional theory (DFT) have been successfully applied to screen stable double perovskites.…”