Structure and Energetics of Dye-Sensitized NiO Interfaces in Water from Ab Initio MD and Large-Scale GW Calculations

Abstract

The energy-level alignment across solvated molecule/semiconductor interfaces is a crucial property for the correct functioning of dye-sensitized photoelectrodes, where, following the absorption of solar light, a cascade of interfacial hole/electron transfer processes has to efficiently take place. In light of the difficulty of performing X-ray photoelectron spectroscopy measurements at the molecule/solvent/metal−oxide interface, being able to accurately predict the level alignment by first-principles calculations on realistic structural models would represent an important step toward the optimization of the device. In this respect, dye/NiO surfaces, employed in p-type dye-sensitized solar cells, are undoubtedly challenging for ab initio methods and, also for this reason, much less investigated than the n-type dye/TiO 2 counterpart. Here, we consider the C343-sensitized NiO surface in water and combine ab initio molecular dynamics (AIMD) simulations with GW (G 0 W 0 ) calculations, performed along the MD trajectory to reliably describe the structure and energetics of the interface when explicit solvation and finite temperature effects are accounted for. We show that the differential perturbative correction on the NiO and molecule states obtained at the GW level is mandatory to recover the correct (physical) interfacial energetics, allowing hole transfer from the semiconductor valence band to the highest occupied molecular orbital (HOMO) of the dye. Moreover, the calculated average driving force quantitatively agrees with the experimental estimate.

Hydration Mechanisms of Tungsten Trioxide Revealed by Water Adsorption Isotherms and First-Principles Molecular Dynamics Simulations

“…First, no spontaneous dissociation of water molecules was observed on the surface, in contrast to what was observed during the DFT-MD simulation of hydrated NiO surfaces by some of us, confirming that water dissociation requires a rather large activation energy on the (001) WO 3 surface. Moreover, the molecular mechanisms involved in the adsorption of the water molecules were roughly the same as those predicted at 0 K. The first 8 water molecules were coordinated to the five-coordinated surface W 5c atoms with an average O w –W 5c bond length of 2.38 Å.…”

“…Given these appealing advantages as a standalone or combined photocatalyst in various heterojunctions, WO 3 has been the subject of many experimental − and theoretical studies − in recent years. In particular, the solid/liquid interfacial properties, crucial for the efficiency of photocatalytic processes, − have been theoretically investigated in the case of the WO 3 /water interface. ,, Previous computational studies have indeed addressed the fundamental understanding of the adsorption of water molecules on the γ-(001) surface [hereafter indicated as (001)]. ,,, Most of the reported studies have shown that water adsorbs preferentially in a molecular (undissociated) form since under-coordinated W atoms at the (001) surface are Lewis acids able to coordinate a water molecule …”

Adsorption Geometries and Electronic Properties of a Dipolar Phosphonate-Based Monolayer on the NiO Surface

“…The energetics reported in this work are based on the total energies and orbital levels obtained by a GGA functional (PBE) corrected by a Hubbard term for the Ni d-orbitals. We are aware that the accuracy of this approach has some limitations and might be cured by many-body perturbation theories as shown, for example, in refs and . Nevertheless, we believe that our results are sufficiently accurate for the conclusions drawn in this work.…”

First‐Principles Modeling of the Adsorption Mechanism of Carboxylic and Phosphonic Acids onto Pristine and Defective Delafossite CuAlO2 Surfaces

“…[6,[43][44][45] Over the last decades, ab initio investigations have been proven to be a valuable tool for getting atomistic insights into the grafting mechanism of molecular sensitizers onto semiconductor slabs, supporting experiments in optimizing the structure and charge generation properties of dye-semiconductor interfaces and providing fundamental understandings of the relevant phenomena governing the DSSCs functioning. [5,37,39,41,[46][47][48][49][50][51][52][53][54][55][56][57][58] Nevertheless, while a large number of theoretical works have addressed the dye adsorption on the TiO 2 surfaces (see for instance refs. [37,59], and references therein), only a few computational studies have appeared so far on the adsorption of anchoring groups or dyes on p-type semiconducting surfaces.…”