Range separated hybrid density functional study of organic dye sensitizers on anatase TiO$_2$ nanowires

TL;DR

This study uses advanced density functional theory to analyze how organic dye molecules adsorb on anatase TiO2 nanowires, affecting their electronic properties and potential for improved solar energy conversion.

Contribution

It provides a detailed computational analysis of dye adsorption modes, electronic structure modifications, and solvation effects on TiO2 nanowires, highlighting implications for solar cell efficiency.

Findings

C2-1 exhibits stronger bidentate binding than coumarin.

Adsorption influences the electronic band structure and absorption spectra.

Solvation effects alter dye binding characteristics.

Abstract

The adsorption of organic molecules coumarin and the donor-$\pi$-acceptor type tetrahydroquinoline (C2-1) on anatase (101) and (001) nanowires have been investigated using screened Coulomb hybrid density functional theory calculations. While coumarin forms single bond with the nanowire surface, C2-1 additionally exhibits bidentate mode giving rise to much stronger adsorption energies. Nonlinear solvation effects on the binding characteristics of the dye chromophores on the nanowire facets have also been examined. These two dye sensitizers show different electronic charge distributions for the highest occupied and the lowest unoccupied molecular states. We studied the electronic structures in terms of the positions of the band edges and adsorbate related band gap states and their effect on the absorption spectra of the dye-nanowire combined systems. These findings were interpreted and discussed from the view point of better light harvesting and charge separation as well as in relation to more efficient charge carrier injection into the semiconductor nanowire.