Designed complexes based on betanidin and L0 Dyes for DSSCs: thermodynamic and optoelectronic properties from DFT study

A combination of natural betanidin (Bd) or decarboxylated betanidin (dBd) dyes possessing efficient carboxylic anchoring groups with synthetic dye L0 containing strong electron donor triphenylamine moiety has been engineered on purpose to improve the dye's optoelectronic properties for DSSCs application. Novel complex D-pi-A organic dyes, L0-Bd and L0-dBd with structural isomers, have been designed via esterification reactions. The DFT/B3LYP5/6-31G(d,p) approach is used in computations of geometry, vibrational spectra and thermodynamic characteristics of complexes; the TD-DFT method - for optoelectronic properties. Due to the combination, broader coverage of the solar spectrum with greater light-harvesting efficiency of the designed sensitisers was achieved compared to individual dyes. The dye complexes ' attachment to the TiO2 cluster was simulated in terms of the different possible adsorption modes; binding energies and electronic spectra of the dye@TiO2 systems were computed, and electron density distributions over frontier molecular orbitals were analysed.

Automated summary

This study combines natural betanidin or decarboxylated betanidin dyes with a synthetic dye to improve the optoelectronic properties for DSSCs application. The designed sensitisers achieved a broader coverage of the solar spectrum and greater light-harvesting efficiency compared to individual dyes. The attachment of dye complexes to TiO2 cluster and their electronic properties were also analyzed.