Electronic Structure of Low‐Dimensional Inorganic/Organic Interfaces: Hybrid Density Functional Theory, G₀W₀, and Electrostatic Models

Abstract

First‐principles simulations of electronic properties of hybrid inorganic/organic interfaces are challenging, as common density functional theory (DFT) approximations target specific material classes like bulk semiconductors or gas‐phase molecules. Taking as a prototypical example anthracene (ANT) physisorbed on monolayer MoS2, the ability of different ab initio schemes to describe the electronic structure using semilocal and hybrid DFT is assessed. For the latter, an unconstrained three‐parameter range‐separation scheme is used. Comparisons against results from the many‐body perturbation theory indicate that properly parametrized hybrid functionals can approximate with reasonable accuracy the quasiparticle properties of both ANT and MoS2 taken by themselves. However, this is not the case for the hybrid interface, where neither functional can predict the correct‐level alignment nor provide a particularly good starting point for G 0 W 0 calculations. It is shown that nonempirically parametrized electrostatic models can accomplish the same task at negligible computational costs. Such schemes can include substrates of hybrid interfaces in good agreement with experimental data. The results indicate that currently, fully atomistic, many‐body simulations of weakly interacting hybrid systems are not worth the required computational resources. In contrast, ab initio‐parametrized effective models mimicking the environment offer a scalable alternative without compromising accuracy and predictivity.

Evidence for Hybrid Inorganic–Organic Transitions at the WS2/Terrylene Interface

“…These calculations were shown to have a similar accuracy to more expensive methods, while further including the geometry of the heterostructure. [44] However, these calculations do not include microscopic effects such as interface dipoles that cause charge transfer across the interface due to Fermi energy alignment. In the case of the similar perylene molecule on WS 2 , calculations reveal an interfacial dipole pulling electrons toward WS 2 .…”

“…[66] This approach is based on the finding that PBE0 gives reasonable estimates for bandgaps of transition metal dichalcogenides, but poor ones the mid-gap position, while the opposite is true for PBE. [44] PBE-based norm-conserving and fully relativistic SG15 pseudopotentials are employed, [67,68] k-and q-grids of 12 Â 12 and 6 Â 6 are used, respectively, the latter sampling the Brillouin zone for the evaluation of the exact-exchange integrals. Plane-wave kinetic energy cutoffs are set to 40, 160, and 120 Ry for wave functions, density, and Fock exchange, respectively.…”

“…The bandgap renormalization due to screening is calculated by solving Poisson's equation for a point charge situated in a dielectric slab of thickness 5.35 Å representing WS 2 , sandwiched between semi-infinite dielectrics corresponding to the substrate and the aggregate. [44] These media are separated from the WS 2 slab by 0.95 Å of vacuum each. The dielectric constant of the fused silica substrate is taken to be ε s ¼ 3.9, while those of WS 2 (ε ⊥ ¼ 11.33, ε k ¼ 15.21) and the aggregate (ε a ¼ 3.2) are calculated from first principles, as described in the next paragraph.…”

Electronic properties of MoSe2 nanowrinkles

“…To map the band structures of the nanowrinkles from the orthorhombic representation adopted in their calculations onto the hexagonal Brillouin zone (BZ) of the pristine monolayer, we applied an unfolding procedure 54–56 implemented in-house. 57,58 To this end, we introduce the spectral functionto assign the corresponding weight to each state in the target representation. In eqn (2), ε n ( k′ ) is the energy of band n at the point k′ of the supercell.…”

Quantum Dots in Transition Metal Dichalcogenides Induced by Atomic-Scale Deformations

“…This choice minimizes the amount of inequivalent supercell K vectors onto which the k vectors along the path map. A symmetric scissor operator is applied to open the bandgap by a quantity given by the difference between the PBE band gap in the flat material and 2.15 eV, corresponding to the value measured when the material is adsorbed on a strongly screening substrate . For real-space visualizations of geometries, we employ XCrysDen …”