  The study of topological quantum materials for enhanced thermoelectric energy
conversion has received significant attention recently. Topological materials
(including topological insulators and Dirac/Weyl/nodal-line semi-metals) with
unique nature of band structure involving linear and regular parabolic bands
near Fermi level (E$_F$) have the potential to show promising TE properties. In
this article, we report the promising TE performance of a quaternary
chalcogenide (Cu$_2$ZnGeTe$_4$) having non-trivial topological phase. At
ambient condition, the compound is a narrow band gap (0.067 eV) semiconductor,
with a TE figure of merit (ZT) 1.2. Application of 5% strain drives the system
to a topologically non-trivial Weyl semi-metal with the right combination of
linear and parabolic bands near E$_F$, giving rise to a reasonable ZT of 0.36.
Apart from strain, alloy engineering (Sn substituted at Ge) is also shown to
induce topological non-triviality. The present work demonstrates the potential
of such unique semimetals for exceptional electronic transport properties and
hence excellent thermoelectric performance.
