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 BaNX (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 BaNF and BaNCl 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 BaNF is longer than BaNCl. 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 V/K at 300K. The ZT values are found to be 1.23 for BaNF while 0.9 for BaNCl 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.

中文翻译：

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Ba3NX3 (X=F, Cl) 钙钛矿的高热电和光电特性：DFT 计算的见解


研究人员正在努力寻找智能高效的材料来应对能源危机。其中，钙钛矿因其在能量收集中的作用而被研究人员广泛探索。在这项研究中，利用密度泛函理论技术探索了卤化物钙钛矿BaNX（X = F，Cl）的结构、弹性、电子、光学和热电性质。容差因子和形成能的允许值确保了这些化合物的结构和热力学稳定性。能带结构计算表明，两种材料都具有半导体性质，BaNF 和 BaNCl 的带隙分别为~2.1 eV 和 1.9 eV。弹性常数表明这两种化合物具有机械稳定性并表现出延展性。研究了 0-40 eV 光子能量范围内的光学响应。在 2 eV 至 25 eV 范围内观察到吸收峰。此外，观察到 BaNF 的弛豫时间比 BaNCl 长。使用 BoltzTrap2 代码获得塞贝克系数、电导率、电子热导率和品质因数 (ZT) 等热电特性。据观察，两种材料的塞贝克系数在 300K 时具有几乎相同的最大值 1.54 × 10 V/K。 700K 时，BaNF 的 ZT 值为 1.23，BaNCl 的 ZT 值为 0.9。这项工作表明，这些卤化物钙钛矿具有很大的潜力，可以证明自己是太阳能电池和热电设备的最佳候选者。