Exploring the effect of halogens on semiconducting nature of boron doped molecular precursor graphene nanoribbons at molecular and bulk level

Abstract

The graphene nanoribbons (GNRs) have been established for device applications in numerous fields due to their superb electro-optical properties. GNRs are used in many nanoscale electronic devices, e.g., solar cells, semiconductors, field effect transistors and nonlinear optics. The isolated molecule precursor of boron doped GNR parent compound 5,10-bis(10-bromoanthracene-9-yl)-5,10-dihydroboranthrene (Br-GNR) and its newly designed derivatives 5,10-bis(10-fluoroanthracene-9-yl)-5,10dihydroboranthrene (F-GNR) and 5,10-bis(10-chloroanthracene-9-yl)-5,10dihydroboranthrene (Cl-GNR) were optimized using density functional theory (DFT) at PBE0/6-311G* level. By replacing the –Br by –F atoms in Br-GNR, the ionization potential (IP) and electron affinity (EA) declined. The hole and electron reorganization energies (λ(h)/λ(e)) of halogenated doped GNRs has been systematically compared with some standard hole and electron transfer materials. The smaller λ(h) values are showing that the studied compounds would be superior hole transfer candidates. The density of states and optical properties at bulk level (including dielectric function, refractive indices, conductivity and loss function) have been probed. The polarizability (γ) amplitudes of F-GNR, Cl-GNR and Br-GNR are 34, 21 and 22 times larger than that of para-nitroaniline at same PBE0/6-311G* level. The calculated non-linear optical (NLO) polarizability amplitudes, optoelectronic and charge transfer properties showed that all the compounds would be good contenders for NLO and semiconductor devices.