  Novel intrinsic two-dimensional materials have attracted many researchers'
attention. The unusual transport and optical properties of these materials
originate mainly from triangular lattices (TLs). Therefore, the application of
energy harvesting calls for a study of the thermoelectric properties of 2D TLs
coupled to electrodes. The transmission coefficient of 2D TLs is calculated by
using the Green's function technique to treat ballistic transports. Especially
important among our findings is the electron-hole asymmetric behavior of the
power factor ($PF$). Specifically, the maximum $PF$ of electrons is
significantly larger than that of holes. At room temperature, the maximum $PF$
of electrons is dictated by the position of the chemical potential of
electrodes near the band edge of TLs. The enhancement of $PF$ with increasing
electronic states results from the enhancement of electrical conductance and
constant Seebeck coefficient. When the band gap is ten times larger than the
thermal energy, it is appropriate to make one-band model predictions for
thermoelectric optimization.
