First-principles calculation of electronic energy level alignment at electrochemical interfaces

Abstract

Energy level alignment at solid-solvent interfaces is an important step in determining the properties of electrochemical systems. The positions of conduction and valence band edges of a semiconductor are affected by its environment. In this study, using first-principles DFT calculation, we have determined the level shifts of the semiconductors TiO2 and ZnO at the interfaces with MeCN and DMF solvent molecules. The level shifts of semiconductor is obtained using the potential difference between the clean and exposed surfaces of asymmetric slabs. In this work, neglecting the effects of present ions in the electrolyte solution, we have shown that the solvent molecules give rise to an up-shift for the levels, and the amount of this shift varies with coverage. It is also shown that the shapes of density of states do not change sensibly near the gap. Molecular dynamics simulations of the interface have shown that at room temperatures the semiconductor surface is not fully covered by the solvent molecules, and one must use intermediate values in an static calculations.

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“…Integrated planar charge density along z-axis normal to (x, y) plane has also been computed for confirmation of charge redistribution for a more thorough understanding of dopant function with different charge states. With the aid of this equation, we evaluated the periodic geometry of a super cell in the (x, y) plane and averaged the density over the (x, y) plane [32].…”

A Green’s Function Approach for Determining Surface Induced Broadening and Shifting of Molecular Energy Levels

“…Interfaces between molecules and solid surfaces are central components in emerging electrochemical technologies. − Upon adsorption of a molecule onto a surface, the molecular energy levels (MELs) are broadened and realigned due to the influence of the electronic states of the solid, which directly affect the energy barrier and efficiency of electron transfer across the interface. ,,,,− Knowing the changes in MEL alignment and broadening is crucial in molecular electronics, ,− electrochemical device design, ,,− , and heterogeneous catalysis, − as it can help identify which MELs participate in the electron transfer process. The importance of energy alignment is evident from Fermi’s golden rule, which guarantees resonance between initial and final energies.…”