Graphene infrared light emitting diode (GILED)
  The present Letter proposes a device based on graphene for infrared light emission. It is based on a n- and p-doped monolayer graphene (MGs), with Fermi energies $E_F$ and -$E_F$, respectively, sandwiching a bilayer graphene (BG) with bandgap $\Lambda=2|eV_g-\Delta|\geq 2E_F$, where $V_g$ is the gate voltage across the BG and $\Delta$ the sub-lattice energy difference into each layer of the BG. This device works as simple as tuning the gate voltage to decrease the BG bandgap down to $2E_F$; and, once this condition is fulfilled, a current flows from the n-doped MG to the p-doped MG. However, when electrons achieve the other side of the device, i.e., into the p-doped MG, their energies ($E_F$) are much bigger than the holes energies ($-E_F$), and thus these electrons decay emitting infrared photons. 
Z.Z. Alisultanov, M.S. Reis
cond-mat.mes-hall