The electronic and optical properties of polythiophene (PT) for polymer light-emitting diodes (PLEDs) were calculated using density functional theory (DFT) time-dependent DFT. We the thiophene PT polymers with degrees polymerization (DP) from 2 to 30 monomers (T1–T30) their derivatives. associated highest occupied molecular orbital (HOMO) energy, lowest unoccupied (LUMO) band gaps, electron orb...

In the present work, the structural and electronic properties, and conductivity of (5,5) and (6,6) Single Walled Carbon Nanotubes in the ground state have done by using the Hartree-Fock and density functional theory DFT-B3LYP/6-31G* level. Delocalization of charge density between the bonding or lone pair and antibonding orbitals calculated by NBO (natural bond orbital) analysis. These methods a...

with the aim of recognizing the steric effects on the silylenic r2c6h6si structures, dft calculationsare carried out on 8 structures of r2c6h6si (where r is hydrogen (h), methyl (me), isopropyl (i-pro),and tert-butyl (tert-bu)). these species are at either triplet (t) or singlet (s) states. singlet–tripletenergy separations ( me (20.32) > t-bu (15.92).all singlet states of r2c6h6si, are more st...

Important parameters of an organic semiconductor material are the electronic band gap (Eg) and position highest occupied lowest unoccupied bands versus vacuum. These called valence conduction for inorganic semiconductors. For semiconductors defining often molecular orbital (HOMO) (LUMO). One advantage semiconducting polymers is ability to tune HOMO LUMO levels by chemical design. The photovolta...

In this communication we provide the first UHV-STM images and STM-based current-voltage (I-V) and orbital mediated tunneling spectroscopy (OMTS) data on a self-assembled porphyrin nanostructure at the single structure level. We will show that transverse conductivity over distances less than 10 nm can occur by barrier type tunneling but that long distance conduction solely occurs through the LUM...