  The role of electron-phonon scattering in thermoelectric transport has been
paid much attention, especially in multivalley systems. By investigating a
two-valley model with electron-phonon coupling, we find three electron
transport regimes realized by electron-hole asymmetry of electron relaxation
time due to the strong intervalley scattering. Seebeck coefficient denotes an
electron-hole dichotomy due to this asymmetry. Also, the strong intervalley
scattering can enhance power factor. Our finding sheds light on unexplored
thermoelectric transport under the strong electron-phonon scattering.
