▎ 摘　　要

The thermoelectric properties of graphene-hBN nanoribbons with substitutional transition metal impurities (Cr, Mn, Fe, Co, Ni) are investigated in the framework of constrained spin density functional theory calculations. The focus on atomic-sized thermoelectric devices is not only supported by the benefits of scaling but also by the enhanced thermopower, which arises from typically sharp variations of the device conductance. Some of the investigated structures present a change in the sign of the Seebeck coefficient by raising the temperature, as a direct consequence of resonant electron transmission. Different transition metal substitutions on boron and nitrogen atoms are investigated comparatively and an overall enhancement of the thermopower and figure of merit is found.