Tunable Band Gap in Bilayer Graphene by Trimesic Acid Molecular Doping

We are presenting the results of first-principles study of the electronic band structure properties of molecular doping of bilayer graphene with one-sided adsorption of a single and self-assembled trimesic acid (TMA) monolayer which exhibits a p-type dopant semiconductor. Our study demonstrates that the effect of charge transfer between the adsorbate and substrate is the origin of perturbation in inversion symmetry of bilayer graphene and a result of band gap opening. Meanwhile, doping of bilayer graphene with an organic molecule produces an internal electric (built-in) field between the bottom and top layer due to charge asymmetry. The self-assembly of trimesic acid (TMA, benzene-1,3,5-tricarboxylic acid) on bilayer graphene with the two most network arrangements improves the stability and band gap energy of the adlayer by formation of reliable hydrogen bonding. The various patterns applied to adsorption on bilayer graphene allow us to tune the induced band gap where the existence of a linear trend of energy gap with number of carriers demonstrates consistency between experimental and theoretical studies. Accordingly these data lead to further implications for nanoelectronics and nanophotonics devices.