Electrical characteristics of Au substituted 2,6-Bis-phenylethynyl-dithieno[3,2-b;2′,3′-d]thiophene (BPDTT) molecule against external electric fields: A quantum chemical and charge density study

The charge density analysis and the electronic structure calculation has been carried out theoretically to understand the effect of external electric field on a newly designed molecular nanowire, 2,6-Bis-phenyl-ethynyl-dithieno[3,2-b;2',3'-d]thiophene (BPDTT) using density functional theory (DFT) with the LANL2DZ basis set. The external electric field was applied in the range of +/- 0.26 V A(-1) which significantly alters the conformation as well as electronic energy levels of the molecule. Further, the applied electric field reduced the frontier molecular orbital energy values from 1.879 to 0.377 eV and also increases the dipole moment of the molecule from 1.41 to 59.1 D. The current-voltage characteristic of the molecule has been calculated theoretically using Landauer formalism. On the whole, the present study reveals the energy level shifting, bond topological features and the electrostatic properties of the molecule for various applied electric fields. (C) 2012 Elsevier B.V. All rights reserved.