First-principles investigation of the thermoelectric characteristics of aluminum-doped graphene

Based on first-principles density functional theory, this paper systematically investigates the effects of aluminum (Al) doping at various concentrations (ranging from 3 to 12 at. %) on the electronic structure and thermoelectric properties of graphene. Al doping introduces impurity levels, converting graphene into a direct-bandgap p-type semiconductor. The bandgap width exhibits a monotonic increase with doping concentration, progressively widening from 0.33 eV at 3 at. % to 1.38 eV at 12 at. %. Concurrently, the density of states near the Fermi level significantly increases with higher Al doping concentrations, which effectively improves the Seebeck coefficient of graphene. Furthermore, high-concentration Al doping improves the electrical conductivity of graphene by introducing holes. The product of the Seebeck coefficient and electrical conductivity (σS2) shows a substantial increase, which predominantly drives the enhancement of the thermoelectric figure of merit (ZT). In particular, for graphene with 12 at. % Al doping, the Seebeck coefficient at 1150 K rises by more than 40 times compared to intrinsic graphene, while the electrical conductivity increases by ∼100 times. This leads to a final ZT value of 0.08, which represents a 478-fold increase relative to pristine graphene. This research elucidates the impact of Al doping on the thermoelectric performance of graphene, providing a theoretical foundation for designing high-efficiency two-dimensional thermoelectric materials through doping strategies. It also computationally confirms the potential of high-concentration Al-doped graphene for applications in thermoelectric conversion.