Computational modeling of single- versus double-anchoring modes in di-branched organic sensitizers on TiO2 surfaces:
Joaquín Calbo1, Mariachiara Pastore, Edoardo Mosconi
1Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Spain. enrique.orti@uv.es.
Abstract:
We present a first-principles DFT investigation of the adsorption geometry on the anatase (101) surface of a prototypical di-branched organic dye based on the extended tetrathiafulvalene moiety, incorporating two anchoring cyanoacrylic acid units. Reduced model systems with one and two anchoring groups have been initially studied to investigate the vibrational frequencies related to TiO2 dye adsorption. Our calculations confirm that the reduced systems can be used as reliable models to study the anchoring modes and that the conclusions extracted from the reduced systems can be extrapolated to the entire molecule. A series of molecular structures have been investigated to simulate the anchoring environment in monodentate- and bidentate-like adsorption modes. The comparison between the theoretical results and the available experimental data suggests a di-anchored monodentate adsorption mode as the most probable adsorption structure. Geometry optimizations of the di-branched model system adsorbed on a periodic slab of anatase (101) allowed us to compare the relative stability of different adsorption conformations and led to a di-anchored monodentate mode as the most stable adsorption structure. Furthermore, ab initio molecular dynamics simulations confirmed this structure as the preferred one, providing additional stabilization by effective hydrogen-bonding to surface oxygens and structure distortion from planarity. The analysis of the partial density of states for the prototypical models confirms that the doubly anchored adsorption provides improved electronic properties compared to the singly anchored structures for dye-sensitized solar cell purposes.
More Related Videos
13:58Probing C84-embedded Si Substrate Using Scanning Probe Microscopy and Molecular Dynamics
Published on: September 28, 2016
06:49In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation
Published on: March 2, 2021
Related Concept Videos
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than...
02:16Resonance and Hybrid Structures
Resonance Structures and Resonance Hybrids
The Lewis structure of a nitrite anion (NO2−) may actually be drawn in two different ways, distinguished by the locations of the N–O and N=O bonds.
01:18Structure of Benzene: Molecular Orbital Model
01:24π Molecular Orbitals of 1,3-Butadiene
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:18Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group...