Range-separated hybrid functionals for mixed dimensional heterojunctions: Application to phthalocyanines/MoS2

Abstract

We analyze the electronic structure and level alignment of transition-metal phthalocyanine (MPc) molecules adsorbed on two-dimensional MoS2 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 molecules and two-dimensional materials, 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 MoS2 valence resonance with the transition-metal phthalocyanine non-frontier 3d orbitals and its dependence on the transition-metal atomic number. Based on our calculations, we derive parameter-free model self-energy corrections that quantitatively account for the effects of the heterogeneous dielectric environment on the electronic structure of these mixed-dimensional heterojunctions.