Half Huesler (HH) alloys have been a hot topic of research due to their fascinating properties and applications in several fields. There are several HH alloys been studied and this work is based on three Bismuth based HH alloys, ZrRhBi, ZrIrBi and HfRhBi, of which we have presented an extensive study on the structural, electronic, thermoelectric (TE) and optical properties using ab-initio density functional theory (DFT) calculations. The previous work on these alloys reported their stability and electronic properties stating that they possess good TE response which was done using DFT with PBE-GGA functional (J. Mater. Chem. A, 5 (13), 2017). In our study, we have used different exchange functionals to investigate these properties and observed that using nmBJ (new modified Becke–Johnson) potential, we can obtain enhanced band gap and TE response (high figure of merit, ZT and power factor, PF) of these alloys as compared to previous report and fascinating optical properties as well. Our results show that ZrIrBi and HfRhBi are narrow-gap and ZrRhBi is a moderate gap semiconductor. All of these alloys have excellent ZT values of around 0.7 at room temperature. The optical properties show that these compounds have low absorbance, moderate reflectivity and low optical conductivity in visible region. The contrasting behaviour of their optical properties with respect to the regions of electromagnetic spectrum and their electronic properties suggests that they can be effectively used in optoelectronics and various optical devices. Also, their high ZT values both in low and high temperatures open up a possibility to use them for various TE applications.

Half Huesler（HH）合金由于其引人入胜的性能和在多个领域的应用而成为研究的热点。已经研究了几种HH合金，并且这项工作基于三种基于铋的HH合金ZrRhBi，ZrIrBi和HfRhBi，其中我们已经使用Ab-initio进行了有关结构，电子，热电（TE）和光学性质的广泛研究。密度泛函理论（DFT）计算。这些合金的先前工作报告了它们的稳定性和电子性能，表明它们具有良好的TE响应，这是通过使用具有PBE-GGA功能的DFT完成的（J.Mater.Chem.A， 5 （13），2017年））。在我们的研究中，我们使用了不同的交换功能来研究这些性质，并观察到使用nmBJ（新改良的Becke-Johnson）电势，我们可以获得增强的带隙和TE响应（高品质因数，ZT和功率因数，PF）与以前的报告相比，这些合金的光学特性也令人着迷。我们的结果表明ZrIrBi和HfRhBi是窄带隙，ZrRhBi是中等间隙半导体。所有这些合金在室温下的ZT值均约为0.7。光学性质表明这些化合物在可见光区具有低吸收率，适度的反射率和低光学导率。它们的光学性质相对于电磁频谱区域及其电子性质的对比行为表明，它们可以有效地用于光电和各种光学器件中。而且，它们在高温和低温下的高ZT值都为将其用于各种TE应用打开了可能性。