First-principle simulations of inorganic halides Li2TlBiY6 (Y = Cl, Br, I) for optoelectronic applications

In this emerging technological era, lead-free (Li-based) inorganic halides have drawn a lot of researchers’ consideration due to their optoelectronic applications. Based on this, we explored theoretically mechanical, optical, and thermoelectric features of halides Li2TlBiY6 (Y = Cl, Br, I) by employing first-principle simulations (Wien2k code). Our finding of optoelectronic parameters using appropriate mBJ approach is in favorable alignment to previously reported data, and PBEsol is employed to scrutinize structural as well as mechanical features of these materials. The Born stability and formation energy are examined concerning the structural stability associated with all halides. The distinction between brittle and ductile nature is investigated concerning the calculation of elastic constants of the cubic symmetry. Being based on the mBJ potential, the bandgasps for Li2TlBiCl6, Li2TlBiBr6, and Li2TlBiI6 are 2.8 eV, 2.3 eV, and 1.9 eV, correspondingly. To confirm their optimal absorbability in the electromagnetic domain (visible), all halides were further analyzed concerning dielectric parameters. Additionally, thermoelectric properties are explained in detail within the temperature range of 300-800K using classical Boltzmann theory, making them promising materials for thermoelectric applications.