The Effect of Substitution and Polymerization of 2,7-Divinylcarbazole-benzo-bis-thiadiazole on Optoelectronic Properties: A DFT Study

In this work, we present the study of the conjugated copolymers 2,7-divinylcabazole and benzo-bis-thiadiazole, by the DFT method using the base B3LYP/6-31G (d, p). To evaluate the properties of these systems, we performed structural optimization without geometric restriction. The NBO analysis was obtained by an energy calculation of the DFT-B3LYP method under the atomic base 6-31G (d, p) from the optimized geometries. Calculations of vibratory frequencies of all the structures studied show that they have minima (all frequencies are positive) on the TPES. In order to study the electronic and optical properties, we calculated the HOMO and LUMO energy levels as well as the band gap (Gap energy). The absorption wavelengths of each system were calculated by the TD-DFT method at the functional level WB97XD under the atomic base 6-31G (d, p). DOI: http://dx.doi.org/10.17807/orbital.V13I4.158

The Effect of Polymerization of 2.7-Divinylcarbazole-Benzo-Bis-Thiadiazole on Optical Fiber Properties

The interest of polymer optical fibers (POF) lies in their low cost compared to silica fibers and in their ease of implementation, i.e. robustness, flexibility, low weight and easier connectivity. The first generation of polymer fibers are of the index jump type and are composed of polymethyl methacrylate (PMMA) for the core and a fluorinated polymer for the cladding. The significant attenuation of OPFs in the red and near IR is due to the harmonics of the different vibrational modes of the C–H bonds. The improvement of this parameter requires a shift in the transmission of the polymer towards longer wavelengths. As in the case of inorganic glasses, this requires the development of materials with low fundamental frequency of vibration. The development of graded index structures also allows limiting the modal dispersion inherent to the multi-mode character of POFs. And before the use of certain materials in the electronic fields a study of certain properties was carried out by the DFT method in order to propose the polymers based on carbazole. This study was carried out by the DFT–B3LYP method as functional with the 6-31G (d, p) atomic base to optimize all systems, from monomer to pentamer

Study Optoelectronic and Geometric Properties of New compounds Based on Carbazole-thiophene Bridged for Solar Cells

Theoretical studies have been carried out to predict the structure, electronic, optical and photovoltaic properties of systems based on carbazole - thiophene bridged and X groups (X1: Benzo-[c]-thiophene, X2: Quinolinn-8-ylamine, X3: Benzyl-amine) with or without the strongly attracting chromophore -CHCO2HCN. The optoelectronic and photovoltaic properties improve when some donor and acceptor blocs alternate on the oligomer skeleton since slight band gap are noticed especially for X2 and X3 molecules with chromophore (average value 2.59eV). Indeed, some higher values of λmax (wave-length absorbed) are obtained and the HOMO and LUMO orbitals are correctly located than their homologs semi-conductors like the bis adduct of phenyl-C61-butyric acid methyl ester (Bis-PC61BM). DOI: http://dx.doi.org/10.17807/orbital.v10i7.1322<br /