Theory of covalent adsorbate frontier orbital energies on functionalized light-absorbing semiconductor surfaces

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DOI	Resolve DOI: https://doi.org/10.1021/jz400601t
Author	Search for: Yu, Min; Search for: Doak, Peter; Search for: Tamblyn, Isaac; Search for: Neaton, Jeffrey B.
Format	Text, Article
Subject	density functional theory; energy level alignment; many-body perturbation theory; organic−semiconductor interface; surface polarization; thiophene-functionalized silicon (111)
Abstract	Functional hybrid interfaces between organic molecules and semiconductors are central to many emerging information and solar energy conversion technologies. Here we demonstrate a general, empirical parameter-free approach for computing and understanding frontier orbital energies – or redox levels – of a broad class of covalently bonded organic–semiconductor surfaces. We develop this framework in the context of specific density functional theory (DFT) and many-body perturbation theory calculations, within the GW approximation, of an exemplar interface, thiophene-functionalized silicon (111). Through detailed calculations taking into account structural and binding energetics of mixed-monolayers consisting of both covalently attached thiophene and hydrogen, chlorine, methyl, and other passivating groups, we quantify the impact of coverage, nonlocal polarization, and interface dipole effects on the alignment of the thiophene frontier orbital energies with the silicon band edges. For thiophene adsorbate frontier orbital energies, we observe significant corrections to standard DFT (∼1 eV), including large nonlocal electrostatic polarization effects (∼1.6 eV). Importantly, both results can be rationalized from knowledge of the electronic structure of the isolated thiophene molecule and silicon substrate systems. Silicon band edge energies are predicted to vary by more than 2.5 eV, while molecular orbital energies stay similar, with the different functional groups studied, suggesting the prospect of tuning energy alignment over a wide range for photoelectrochemistry and other applications.
Publication date	2013-04-26
Publisher	American Chemical Society
In	The Journal of Physical Chemistry Letters 4, no. 10: 1701–1706.
Language	English
Peer reviewed	Yes
NRC publication	This is a non-NRC publication "Non-NRC publications" are publications authored by NRC employees prior to their employment by NRC.
NPARC number	23003159
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Record identifier	9e137be5-d524-43b9-9a46-a653d6d64004
Record created	2018-05-03
Record modified	2020-05-30

Date modified:: 2026-01-19