Quasiparticle electronic structure of phthalocyanine-transition metal dichalcogenide interfaces from first-principles GW*

Two-dimensional transition-metal dichalcogenide (TMD) nanostructures have attracted much attention because of their appealing optoelectronic properties. Modulation of these materials is crucial in tuning their properties and consequently widening their applications. Herein, we investigate the modulation of the electronic structure of TMDs by (metallo)phthalocyanine molecules, using first-principles GW. We apply the substrate screening and dielectric embedding approaches to expedite the calculation, and examine the many-body dielectric screening at such molecule-semiconductor interfaces. We show how the gaps of the phthalocyanine molecules and the band structures of TMDs are altered upon formation of the interface. We carefully compare different GW approaches for the heterogeneous interface, for the purpose of method development. Moreover, our calculations provide benchmark results in the quasiparticle energy level alignment at the interface, as well as trends for a series of metallophthalocyanine molecules and TMD substrates. We provide theoretical insight into a few existing experiments and discuss implications of our results.