New materials based on thiazolothiazole and thiophene candidates for optoelectronic device applications: theoretical investigations

We report theoretical analysis on the geometries and electronic properties of new conjugated compounds based on thiazolothiazole synthesized by Ando et al. (Synth. Met., 156:327 [13]). The theoretical ground-state geometry and electronic structure of the studied molecules were investigated by the density functional theory (DFT) method at Becke’s three-parameter functional and Lee–Yang–Parr functional (B3LYP) level with 6-31G(d,p) basis set. The effects of the ring structure and the substituents on the geometries and electronic properties of these materials are discussed to investigate the relationship between molecular structure and optoelectronic properties. This investigation was used to drive further syntheses towards compounds more useful as active optoelectronic materials. Theoretical knowledge of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the components is basic in studying organic solar cells, so the HOMO, LUMO, and gap energy V _oc (open-circuit voltage) of the studied compounds are calculated and discussed. These properties suggest these materials as good candidates for use in organic dye-sensitized solar cells.     

Electronic structure and thermochemistry for monocarbides MC,MC+ and MC− (M=Zn,Cd, Hg): CCSD(T) and DFT works

In this work, the ab-initio coupled cluster CCSD(T) method and the B3LYP, BP91W and CAM-B3LYP functional of DFT method in conjunction with the aug-cc-pVTZ-PP basis have been applied to study the group 12 monocarbides MC, MC⁺ and MC^?. The potential energy curves (PECs) for the three electronic states ³Σ^?, ⁵Σ^? and ¹Δ of the MC and the two states ²∑^- and ⁴∑^- for the MC⁺ cations and MC^? anions have been investigated. In addition, Bond distance Re, transition energy Te, vibrational frequency ω_e, ionization energy IE, electron affinity EA, dipole moment μ, dissociation energy D₀ and heat formation ΔH°f₀/ΔH°f₂₉₈, were determined for each species. The analysis of the dissociation energy for ZnC, CdC and HgC shows the decrease in the stability of the monocarbides from Zn to Hg. For ΔH°f₀/ΔH°f₂₉₈ values of MC, which are not known experimentally or theoretically, we recommend the following CCSD(T) predictions of ZnC, CdC and HgC: 181.3/178.54, 180.65/178.4 and 175.35/174.71 kcal/mol respectively. Comparing the three functionals with the CCSD(T) results, the CAM-B3LYP functional shows excellent predictive agreement for the various properties of the group 12 monocarbides.     

Coumarin-based D–π–A dyes for efficient DSSCs: DFT and TD-DFT study of the π-spacers influence on photovoltaic properties

Research on Chemical Intermediates - A series of D–π–A architectures dyes with Coumarin-based derivatives as difluorenylaminocoumarin (DF) and diphenylaminocoumarin (DP) have been...     

Interactions of peptides with metallic cations. I. Complexes glycylglycine–M (M=Li, Na)

In view of better understanding interactions of aminoacids and peptides with metallic cations, in the isolated state and in water, the model system glycylglycine–M⁺ (M=Li, Na) has been studied theoretically. The computations have been performed with the help of the density functional theory (DFT) and the B3LYP functional. The extended basis set was the standard 6-31++G**. In solution we used a recent model of continuum with a multicentric multipole expansion of the charge distribution. Our study shows that low energy complexes with lithium and sodium are rather similar. In the isolated state, the most stable form corresponds to a bidentate complex in which the cation interacts with two oxygen atoms, one from the terminal COOH and one from the amidic carbonyl. In solution, the coordination of the cation in the most stable form is 3, the nitrogen of the end amino group being the third ligand.

The energy range between the lowest energy structure and the highest energy one, in both cases, is slightly reduced under the electrostatic influence of the solvent.     

Benzocarbazole-based D–Di–π–A dyes for DSSCs: DFT/TD-DFT study of influence of auxiliary donors on the performance of free dye and dye–TiO2 interface

Research on Chemical Intermediates - A series of ten organic dyes Ai (i=1–10) of type D–Di–π–A (i=2–10) combining various auxiliary donors (Di) with the same...     

DFT and TD-DFT calculations on thieno[2,3-b]indole-based compounds for application in organic bulk heterojunction (BHJ) solar cells

Research on Chemical Intermediates - Eight novel organic compounds with donor–π–acceptor (D–π–A) structure were designed for use as donors in organic bulk...     

DFT and TD-DFT calculation of new thienopyrazine-based small molecules for organic solar cells

Background

Novel six organic donor-π-acceptor molecules (D-π-A) used for Bulk Heterojunction organic solar cells (BHJ), based on thienopyrazine were studied by density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches, to shed light on how the π-conjugation order influence the performance of the solar cells. The electron acceptor group was 2-cyanoacrylic for all compounds, whereas the electron donor unit was varied and the influence was investigated.

Methods

The TD-DFT method, combined with a hybrid exchange-correlation functional using the Coulomb-attenuating method (CAM-B3LYP) in conjunction with a polarizable continuum model of salvation (PCM) together with a 6-31G(d,p) basis set, was used to predict the excitation energies, the absorption and the emission spectra of all molecules.

Results

The trend of the calculated HOMO–LUMO gaps nicely compares with the spectral data. In addition, the estimated values of the open-circuit photovoltage (V_oc) for these compounds were presented in two cases/PC₆₀BM and/PC₇₁BM.

Conclusion

The study of structural, electronics and optical properties for these compounds could help to design more efficient functional photovoltaic organic materials.