High thermoelectric and opto-electronic properties of Ba3NX3 (X=F, Cl) perovskite: Insights from DFT computation

Researchers are working for discovering smart and efficient materials to cope with energy crises. Amongst them, Perovskite are explored extensively by researchers owing to their role in energy harvesting. In this study, structural, elastic, electronic, optical and thermoelectric properties of halide perovskites Ba 3 NX 3 (X = F, Cl) have been explored by using density functional theory techniques. The permissible values of tolerance factor and formation energy ensure the structural and thermodynamic stability of these compounds. Band structure calculations revealed that both materials have semiconducting nature, with the band gap of ∼2.1 eV and 1.9 eV for Ba 3 NF 3 and Ba 3 NCl 3 respectively. The elastic constants suggest both compounds are mechanically stable and exhibit ductile nature. Optical response is studied in the energy range of 0–40 eV of photons. The absorption peaks are observed from 2 eV to 25 eV. Furthermore, it is observed that the relaxation time for Ba 3 NF 3 is longer than Ba 3 NCl 3 . Thermoelectric properties such as Seebeck coefficient, electrical conductivity electronic thermal conductivity and figure of merit (ZT) are obtained using BoltzTrap2 code. It is observed that for both materials Seebeck coefficient has almost same maximum value of 1.54 × 10 −3 V/K at 300K. The ZT values are found to be 1.23 for Ba 3 NF 3 while 0.9 for Ba 3 NCl 3 at 700K. This work demonstrates that these halides perovskites have a lot of potentiality to prove themselves as best candidates for solar cells and for thermoelectric devices. • Physical characteristics of the semiconductor halide perovskites Ba 3 NX 3 (X = F, Cl) are investigated through VASP code. • The compounds are semiconductors with direct band gap. • IR-elast package is used for computation of elastic constant. • Both semiconductors are structurally and mechanically stable. • Figure of merit (ZT) is 1.23 for Ba 3 NF 3 and 0.9 for Ba 3 NCl 3 at 700 K.