Energy-Level Alignment at Organic/Inorganic Interfaces from First Principles: Example of Poly(para-phenylene)/Rock-Salt ZnO(100)

Abstract

By means of full-potential all-electron density-functional theory and many-body perturbation theory, we compute the band alignment at a prototypical hybrid inorganic/organic interface. The electronic properties of a model system built of poly(para-phenylene) and rs-ZnO are studied in two different geometries, employing several approaches of increasing sophistication. To this extent, we explore models for predicting the level alignment, which are based on the knowledge of the electronic structure of the individual constituents and are commonly used for semiconductor interfaces. For their evaluation in the context of hybrid materials, we perform an ab-initio study of the entire system, including a quasiparticle description of the electronic stucture within the G0W0 approximation. Based on this, we quantify the impact of structure, charge redistribution, orbital hybridization, and molecular polarization on the band offsets and the alignment type. We highlight not only known limitations of predicting the level alignment at a hybrid inorganic/organic interface by simple models, but also demonstrate how structural details of the interface components impact the results. arXiv:1908.07293v1 [cond-mat.mtrl-sci]

Ultrafast charge transfer and vibronic coupling in a laser-excited hybrid inorganic/organic interface

“…Since then, extensive research has been carried out on hybrid materials, demonstrating the possibility to tune the band-gap and work function of conventional inorganic semiconductors by means of molecular adsorbates [5,[8][9][10][11][12][13][14][15][16]. In spite of the challenge that these systems and their complexity represent for ab initio methods [17][18][19], tremendous progress has been produced in this field by the synergistic interplay between experiments and first-principles calculations (see, e.g., Refs. [9,12,[20][21][22]).…”

Pentacene and Tetracene Molecules and Films on H/Si(111): Level Alignment from Hybrid Density Functional Theory

“…These observations are at variance with our computational observations for much thinner films, which account for the levels in a single system, i.e., including the electrostatics at the interface. [59] It seems possible that differences in film thickness and substrate doping might lead to different level alignment between our computational results and the experimental observation by MacQueen et al On the other hand, our calculations are performed for the combined film-substrate system, not for separate film and substrate systems that were used to deduce alignments in the experimental study. Encouragingly, for the combined filmsubstrate system, MacQueen et al [20] observe a hole transfer from the substrate to the Tc film that is consistent with the conclusions drawn from our model system.…”

“…The HOMO and LUMO are hence shifted downward in energy compared to the standing case. Note that varying the hybrid functional [93] or considering dynamical screening effects [94,95,59] might alter the energy levels further. Nevertheless, the results indicate that hole transfer from isolated molecules to the substrate should be more difficult for a standing molecule than for a lying one.…”

“…e.g., in Ref. [59]. In that work, a nearly strain-free interface (poly(para-phenylene)at the rock-salt ZnO(100) surface) was investigated in detail, allowing for small model sizes and thus an analysis of the electronic level alignment up to the G 0 W 0 level of theory.…”

LayerPCM: An implicit scheme for dielectric screening from layered substrates

“…On the other hand, when molecules are physisorbed on a surface, they preserve their intrinsic features to a large extent. Nonetheless, their electronic and optical properties undergo significant variations, including band-gap renormalization [13][14][15][16][17] and reduction of exciton binding energies. 16,18,19 Capturing these effects with the required accuracy represents one of the main challenges for modern electronic structure theory.…”