Enhancement of thermoelectric performance in monolayer AlP3 via Ga and in doping: A first-principles study

Recently, two-dimensional (2D) triphosphides have attracted much attention in the thermoelectric field due to their semiconductor properties and excellent electronic transport properties. In our study, the performances of AlP3, Al0.5Ga0.5P3, and Al0.5In0.5P3 doped monolayers in the thermoelectric transport are studied. First, the dynamic structural stabilities of the three monolayers are verified through phonon dispersion curves. Moreover, all monolayers are indirect band-gap semiconductors, which can be used as thermoelectric materials. The results show that larger electronic relaxation time and carrier mobilities of doped monolayers lead to larger electronic transport parameters and higher dimensionless thermoelectric figure-of-merit (ZT). It is found that after doping via Ga and In, the thermoelectric performances of AlP3 are increased by 1.31–1.79 times. Our findings show that AlP3 and its doped monolayers hold significant promise as thermoelectric materials within the temperature span of 300–700 K and the doping mechanism could significantly improve the thermoelectric properties of 2D structures.