Protonated Carboxyl Anchor for Stable Adsorption of Ru N749 Dye (Black Dye) on a TiO₂ Anatase (101) Surface

Abstract

We have investigated the adsorption stability of ruthenium N749 dye [black dye (BD)], a highly efficient dye for dye-sensitized solar cells (DSCs), through protonated and deprotonated carboxyl group anchors on a TiO2 anatase (101) surface by using first-principles calculations. Geometry optimizations of the surface system with a supercell and the UV-visible spectrum calculation of the optimized dye structure were carried out. Among the configurations with one and two anchors, the BD adsorption anchored with one protonated carboxyl group was found to be the most stable, in contrast to most previous reports. Hydrogen bonding between the proton retained in BD and the surface oxygen is responsible for the stability of the protonated anchor. We confirmed that the calculated UV-visible spectrum of the most stable dye structure shows the best consistency with the experimental data. It is also demonstrated that the electronic density of states largely depends on the proton position. This novel aspect of adsorption via a protonated carboxyl anchor gives a new perspective for interfacial electronic processes of DSCs.

Vegetable-based dye-sensitized solar cells

“…4c) with the TiO 2 surface, 198 depending on the structure of the dye, the binding groups, the pH, and the metal oxide synthesis. In this regard, polypyridine complexes of d 6 metal, such as Ru(II), 79,81,84 Os(II) 79,84 or Ru(I), 91 are typical examples of compounds characterized by intense bands in the visible region due to MLCT transition. In this regard, polypyridine complexes of d 6 metal, such as Ru(II), 79,81,84 Os(II) 79,84 or Ru(I), 91 are typical examples of compounds characterized by intense bands in the visible region due to MLCT transition.…”

Everything you always wanted to Know about Black Dye (but Were Afraid to Ask): A DFT/TDDFT Investigation

“…We have established that the species BD_2Hll and the BD_1Hc are the most stable diproton-Ve ry recently, the adsorption mode of the BD on TiO 2 has also been computationally investigated using both cluster and periodic boundary conditions approaches. [34][35][36] The optical absorption spectrum of the BD adsorbed onto TiO 2 clusters (BD@TiO 2 ) has also been calculated, [35] although a simplified TiO 2 model was employed which did not allow full exploration of the possible dye binding modes. [36] The work by Sodeyama et al on the other hand, explored in detail the possible dye binding modes on TiO 2 in vacuo, but reported simulated optical properties for the isolated dye at their adsorption geometry.…”

“…[17] Due to the great experimental interest and the high efficiency of the BD, various theoretical studies on this system have been reported. [27][28][29][30][31][32][33][34][35][36] In particular, a few computational works have been focused on the electronic structure of the BD [28] and on the optical properties of the monoprotonated [29] and on the fully protonated, di-and mono-protonated and fully deprotonated forms of BD. [31] Also a study on the electronic structure and absorption spectra of linkage isomers of BD has been reported.…”

Investigation of the influence of coadsorbent dye upon the interfacial structure of dye-sensitized solar cells

“…[9][10][11][12][13][14][15][16] However, it is unclear whether the behavior of dye molecules on a single crystal surface is faithfully reproduced by molecules on nanocrystalline TiO 2 , which is the material used for photovoltaic cell electrodes. Direct observations are very difficult because of the complex structure of nanocrystalline TiO 2 , so a high-resolution method with high specificity is required for observing the microscopic structure of the surface morphology of these porous materials.…”