Enhancement of thermoelectric efficiency of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>T</mml:mi><mml:mtext>?</mml:mtext><mml:msub><mml:mrow><mml:mi>HfSe</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub></mml:math>via nanostructuring

In this work, ab initio calculations based on density functional theory and the Landauer formalism are carried out to investigate ballistic thermoelectric properties of $T\text{\ensuremath{-}}\mathrm{Hf}{\mathrm{Se}}_{2}$ nanoribbons (NRs). The zigzag-edged NRs metallic, they not included in study. armchair possess two types edge symmetries depending number atoms present a row; odd-numbered have mirror symmetry, whereas even-numbered glide reflection symmetry. armchair-edged dynamically stable show semiconducting with varying band gap values infrared visible regions. Detailed transport analyses that $n$-type Seebeck coefficient power factor differ because structural $p$-type coefficients significantly influenced. It is shown phonon thermal conductance reduced third its two-dimensional value via nanostructuring. for $T$-phase $\mathrm{Hf}{\mathrm{Se}}_{2}$ enhanced NRs. We report $ZT$ at 300 800 K by factors 4 3, respectively.