Range-Separated Hybrid Functionals for Mixed-Dimensional Heterojunctions: Application to Phthalocyanines/MoS2

TL;DR

This paper develops a novel tuning procedure for range-separated hybrid functionals in DFT to accurately model the electronic structure and level alignment of transition-metal phthalocyanines on MoS2, matching experimental results.

Contribution

It introduces a multi-objective optimal tuning method for hybrid functionals tailored to mixed-dimensional heterojunctions, improving electronic structure predictions.

Findings

Accurate energy level alignment matching photoemission data

Elucidation of MoS2 valence resonance with phthalocyanine orbitals

Parameter-free self-energy corrections for dielectric effects

Abstract

We analyze the electronic structure and level alignment of transition-metal phthalocyanine (MPc) molecules adsorbed on two-dimensional MoS$_2$ employing density functional theory (DFT) calculations. We develop a procedure for multi-objective optimal tuning of parameters of range-separated hybrid functionals in these mixed-dimensional systems. Using this procedure, which leads to the asymptotically-correct exchange-correlation potential between molecule and two-dimensional material, we obtain electronic structures consistent with experimental photoemission results for both energy level alignment and electronic bandgaps, representing a significant advance compared to standard DFT methods. We elucidate the MoS$_2$ valence resonance with the transition-metal phthalocyanine non-frontier 3$d$ orbitals and its dependence on the transition metal atomic number. Based on our calculations, we derive parameter-free, model self-energy corrections that quantitatively accounts for the effects of the heterogeneous dielectric environment on the electronic structure of these mixed-dimensional heterojunctions.