Aurelie Champagne1,2,Olugbenga Adeniran3,Tomojit Chowdhury4,Mengyu Gao4,Jiwoong Park4,Zhenfei Liu3,Jeffrey Neaton1,2,5
Lawrence Berkeley National Laboratory1,University of California, Berkeley2,Wayne State University3,The University of Chicago4,Kavli Energy NanoScience Institute5
Aurelie Champagne1,2,Olugbenga Adeniran3,Tomojit Chowdhury4,Mengyu Gao4,Jiwoong Park4,Zhenfei Liu3,Jeffrey Neaton1,2,5
Lawrence Berkeley National Laboratory1,University of California, Berkeley2,Wayne State University3,The University of Chicago4,Kavli Energy NanoScience Institute5
Interfacing transition metal dichalcogenides (TMDs) into van der Waals heterostructure bilayers with type-II level alignment has led to recent reports of interlayer excitons with large binding energies, long lifetimes, and signatures of exciton condensation at elevated temperatures [1–4]. Atomically flat two-dimensional molecular crystals (MC) on TMD monolayers is an emerging interfacial quantum materials platform with tunable level alignment, exciton binding energies, and photoluminescence, given the heightened sensitivity of the organic layers to their environment [5]. In addition to non-local adsorbate/substrate screening, free charge carrier screening is particularly relevant in MC-TMD bilayer heterostructures, and controllably altering these distinct modes of screening can lead to new phenomena. Using a dielectric embedding ab initio GW plus Bethe-Salpeter equation (GW-BSE) approach [6], we compute energy level alignment as well as neutral excitations at MC-TMD interfaces (MC = PDI or PTCDA ; TMD = MoS<sub>2</sub> or WS<sub>2</sub>), exploring new emergent optical transitions, such as those associated with interlayer excitons characterized by electrons and holes separated between the MC adsorbate and the TMD, respectively. Combining the GW-BSE approach with a new model we have developed that reduces computational cost with no loss of accuracy [7], we further explore how the presence of free charge carriers can screen the electron-hole interactions and modify the quasiparticle energy level alignment and interlayer excitons.<br/><br/>This work is supported by the Center for Computational Study of Excited-state Phenomena in Energy Materials (C2SEPEM) and the Theory of Materials FWP at LBNL, funded by the US Department of Energy (DOE) under contract No. DE-AC02-05CH11231. Computational resources are provided by the National Energy Research Scientific Computing Center (NERSC).<br/><br/>[1] Fogler et al., Nat. Commun. 5, 4555 (2014); [2] Wilson et al., Nature 599, 383 (2021); [3] Rivera et al., Nat. Nanotechnol. 13, 1004 (2018); [4] Barré et al., Science 376, 406 (2022); [5] Ulman and Quek, Nano Lett. 21, 8888 (2021); [6] Liu et al., J. Chem. Theory Comput. 15, 4218 (2019); [7] Champagne et al., Nano Lett. 23, 4274 (2023).