  Thermoelectric measurements for graphene ribbons are currently performed on
samples that include atomic disorder via defects and irregular edges. In this
work, we investigate the thermopower or Seebeck coefficient of graphene ribbons
within the linear response theory and the Landauer formalism, and we consider
the diffusive regime taken as a limit of the ribbon aspect ratio. We find that
the thermopower and the electronic conductivity depend not only on the aspect
ratio, but also on chemical potential and temperature, which are set here as
key parameters. The obtained numerical results with temperature and doping are
brought into contact with the thermoelectric measurements on disordered
graphene ribbons with good agreement.
