TYC@Imperial: Energy level alignment at semiconductor-water interfaces from atomistic and continuum solvation models

Lars Blumenthal

Department of Physics, Imperial College London

Monday 15th January 2018
Time: 12.00pm
Venue: Room G01, Royal School of Mines, Imperial College London
Contact: Ms Hafiza Bibi
Tel: 02075947252

Abstract: Identifying new photoelectrode systems for more efficient photoelectrochemical cells constitutes a major challenge. A detailed understanding of the electronic structure of photoelectrodes, in particular the alignment of the electrodes' electronic band edge positions with the redox potentials of the chemical reactions of interest, is required to guide experimental progress towards increased efficiencies.
To address this problem, we introduce a new approach [1] based on the combination of many-body perturbation theory within the GW method [2] for the electronic structure of the photoelectrode and joint density functional theory (JDFT) [3] for the description of the electrode-electrolyte and the electrolyte-vacuum interface. Rather than relying on computationally expensive ab initio molecular dynamics, JDFT employs continuum solvation models for the description of the electrolyte. By studying the prototypical photoelectrode material rutile (TiO2), we compare and contrast different continuum and atomistic models of the electrolyte, show that they disagree on the change in electric potential across a single interface, and explain why this is a consequence of different levels of detail in their representations of the charge density. Crucially, we show that, despite this disagreement, the computationally cheap continuum solvation models can still be used for the electronic energy level alignment since the mentioned differences cancel when crossing both the electrode-electrolyte and the electrolyte-vacuum interface.

1. L. Blumenthal, J. M. Kahk, R. Sundararaman, P. Tangney, and J. Lischner. Energy level alignment at semiconductor–water interfaces from atomistic and continuum solvation models. RSC Adv., 2017, vol. 7, no. 69, pp. 43660–43670.

2. M. S. Hybertsen and S. G. Louie. Electron correlation in semiconductors and insulators: Band gaps and quasiparticle energies. Physical Review B, 1986, 34, 5390.

3. S. Petrosyan, J.-F. Briere, D. Roundy, and T. Arias. Joint density-functional theory for electronic structure of solvated systems. Physical Review B, 75, 205105, 2007.


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