Delocalized Carriers and the Electrical Transport Properties of n-Type GeSe Crystals

Recent discovery of a high thermoelectric figure of merit in n-type SnSe single crystal stimulates further research on the analogue compounds. In this work, n-type GeSe is predicted to have a significantly higher normalized power factor along the cross-plane direction based on density functional theory (DFT) calculations and Boltzmann transport theory. This high normalized power factor is due to the high normalized electrical conductivity, which originates from the more delocalized interlayer carrier density. Furthermore, the effects of several potential n-type dopants (group VA and group VIIA elements) on the electronic structure and electrical transport properties of GeSe have been studied. We find that the group VA dopants decrease the density of states near the conduction band minimum and result in a decrease of the Seebeck coefficient of GeSe. As a result, n-type GeSe doped with group VIIA elements is predicted to have a higher normalized power factor than that doped with group VA elements.