Pentacene and poly-pentacene as graphene nanoribbons

• DFT is used to calculate the electronic properties of poly-pentacene (PPC).
• The results show that PPC has the properties of a graphene nanoribbon.
• The band gap is linearly dependent on the K vector near K=0.

The development of electronic devices based on the unique electronic properties of graphene requires the large scale synthesis of graphene nanoribbons which remains a significant challenge. A possible way around this is to seek existing molecules that can be readily chemically synthesized and have the structure of graphene nano-ribbons. One such molecule is pentacene, C22H14, a two dimensional chain of 5 benzene rings.Density functional theory (DFT) is used to examine the electronic and vibrational properties of pentacene, poly-pentacene and its boron nitride analogs. The results show that pentacene and poly-pentacene have similar unique electronic properties to graphene nanoribbons. The HOMO–LUMO energy gap decreases with the length of the chain and the band gap increases with increasing wave vector. In contrast the energy gap for the BN ribbons is relatively independent of the chain length and the wave vector.