Novel diethylaniline D-A-π-A sensitizers for dye sensitized solar cells

2-Hexylthiophene-substituted Alizarin-based (D–π–A) Organic Dyes for Dye-sensitized Solar Cell Applications: Density Functional Theory and UV–Vis Studies

This work reports density functional theory and time-dependent density functional theory calculations of the optimized geometries, electronic structures and optical properties of molecular dyes D1, D2, D3, D4, D5, and D6 formulated through substitution of 2-hexylthiophene to alizarin using the hybrid functional B3LYP and 6-31G (d,p) basis sets. The dyes are considered as potential pigments for dye-sensitized solar cells. For all dyes, HOMO/LUMO (Highest Occupied Molecular Orbital/Lowest Unoccupied Molecular Orbital) analysis results in positive outcomes upon electron injection to semiconductors and subsequent dye regeneration by the electrolyte. It is found that charge transfer is from the thiophene and unsubstituted ring of alizarin to the substituted ring of alizarin containing C=O and OH groups. The C=O groups are observed to be very important in strengthening the dyes as they are revealed to be the anchoring group bonding to the TiO2 semiconductor. Comparatively, dye D6 is observed to possess high absorption ability and electron injection power through a study of the light-harvesting efficiency and injection driving force (Δ Ginject). The estimated values of open-circuit voltage ( Voc) for the computed dyes are also presented. Decisively, all the considered dyes prove to be useful as potential photosensitizers in solar cells using a TiO2 semiconductor and [Formula: see text] coupling electrolyte.

Lawsone isomers, lawsone ether and bilawsone for dye-sensitized solar cells applications: DFT and UV-Vis studies

Structural and optoelectronic properties of lawsone (L), lawsone ether (LE) and bilawsone (BL) were studied theoretically using the DFT and time-dependent DFT methods with hybrid functional B3LYP5 and 6-311G (2d,p) basis set. For the monomer lawsone molecule, isomerization reaction between two rotational isomers was analyzed based on a thermodynamic approach. The electronic spectra of the dyes molecules in a vacuum and solvents (DMSO and CH₂Cl₂) were computed. The maximum wavelengths were found at 355-408 nm for the LE and 350-448 nm for BL that indicated bands shift to visible range compared to L (340 nm). The UV-Vis spectra of the L and BL were measured experimentally in DMSO solution. For the BL, a broad and intensive band was observed in a visible region at 452 nm that apparently would favour sensitizing ability of the dye. The optoelectronic properties of the LE and BL showed them as more promising candidates for DSSCs applications compared to the individual lawsone dye.