Toward a rational design of poly(2,7-carbazole) derivatives for solar cells.

On the basis of theoretical models and calculations, several alternating polymeric structures have been investigated to develop optimized poly(2,7-carbazole) derivatives for solar cell applications. Selected low band gap alternating copolymers have been obtained via a Suzuki coupling reaction. A good correlation between DFT theoretical calculations performed on model compounds and the experimental HOMO, LUMO, and band gap energies of the corresponding polymers has been obtained.

Optical and photophysical properties of indolocarbazole derivatives.

We present a study of the optical and photophysical properties of five ladder indolo[3,2-b]carbazoles, namely, M1, M2, M3, M4, and M5. The ground-state optimized structures were obtained by B3LYP/6-31G* density functional theory (DFT) calculations, whereas the optimization (relaxation) of the first singlet excited electronic state (S1) was performed using the restricted configuration interaction (singles) (RCIS/6-31G*) approach. The excitation to the S1 state does not cause important changes in the geometrical parameters of the compounds, as corroborated by the small Stokes shifts.

A theoretical, spectroscopic, and photophysical study of 2,7-carbazolenevinylene-based conjugated derivatives.

A combined theoretical and experimental study of the structure, optical, and photophysical properties of four 2,7-carbazolenevinylene-based derivatives in solution is presented. Geometry optimizations of the ground states of PCP, PCP-CN, TCT, and TCT-CN were carried out using the density functional theory (DFT/B3LYP/6-31G*). It is found that PCP and TCT are nearly planar in their ground electronic states (S0), whereas the cyano derivatives are more twisted.

A first principles calculations and experimental study of the ground- and excited-state properties of ladder oligo(p-aniline)s.

The molecular structure of three ladder oligo(p-aniline)s, 5,11-diethyl-6,12-dimethylindolo[3,2-b]carbazole (DIMER 2P), 14-ethyl-5,8-dihydro-diindolo[3,2-b:2',3'-h]carbazole (TRIMER 2P), and 5,8,14-triethyl-diindolo[3,2-b:2',3'-h]carbazole (TRIMER 3P) were investigated by first principles calculations at the Hartree-Fock (HF6-31G*) and density functional theory (DFTB3LYP6-31G*) levels. It is found that the agreement between theoretical and x-ray geometrical parameters is good and rather similar for both theoretical methods. The nature and the energy of the first two singlet-singlet electronic transitions have been obtained by Zerner intermediate neglect of differential overlap/spectroscopy semiempirical calculations performed on the HF6-31G* and DFTB3LYP6-31G* optimized geometries, as well as time-dependent density functional theory (TDDFT) calculations performed on the DFTB3LYP6-31G* optimized structures.