Comparison in optoelectronic properties of triphenylamine-imidazole or imidazole as donor for dye-sensitized solar cell: theoretical approach

In the present work, the structural and electronic properties of the D-D'-π-A organic dye with two donors have been calculated theoretically by DFT/time-dependent DFT method. In order to prove their efficiency as sensitizers, a comparative study was performed with a series of D-π-A architecture with one donor. The results of light-harvesting efficiency (LHE), open circuit voltage (Voc), free energy injection (∆G_inj), free energy dye regeneration∆G_reg,excited-state lifetimes for the two series reveal that the D-D'-π-A dyes are promising for the design of new sensitive dyes in solar cells.

The effect of group-substitution on the sensitization properties of alkynylrhenium(I) tricarbonyl diimine complexes adsorbed to TiO2(101) film surface: a theoretical study

A series of dyes are designed by adding the different electron-donating (-CH₃, -NH₂, -OH) and electron-withdrawing groups (-Br, -Cl, -NO₂) to the different ancillary ligands in the alkynylrhenium(I) tricarbonyl diimine complexes [Re(CO)₃(N^N){C≡C-C₆H₄-CH=C(CN)(COOH)}], where N^N = 1,10-phenanthroline (phen)(1) and then investigated the sensitization properties of dyes linked to the TiO₂(101) surface. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to study the electronic structure, frontier molecular orbitals, and absorption spectral properties. The effect of group-substitution on sensitization properties is obvious. When the dye molecules are combined with TiO₂(101) surface, not only the absorptions of some sensitizers containing -CH₃ or -OH groups have red shift but also the electrons can be directly injected into the TiO₂ conduction band from the dye molecules compared with the parent molecular 1. The results indicate that the designed dyes containing electron-donating groups have smaller energy gaps, better light-harvesting efficiency, sufficient driving force, and higher charge transfer efficiency as appropriate dye sensitizers. We hope it can provide valuable hints so that we can design more efficient dye sensitizers in DSSCs.