Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 47: 2D Materials: Heterostuctures

HL 47.6: Talk

Thursday, March 21, 2024, 16:15–16:30, EW 201

Effect of Energy Bands Overlap in the Interlayer Energy Transfer Processes in 2D Heterostructures — •Arka Karmakar — University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland

Heterostructures (HSs) made by the monolayers (1Ls) of transition metal dichalcogenides (TMDs) have shown great promises in designing next-generation optoelectronic device applications. Interlayer charge (CT) and energy transfer (ET) processes are the main photocarrier relaxation pathways in the TMD HSs. CT processes mainly occur due to the energy level offset between the materials and can survive only up to a few nm. Whereas, the interlayer ET process mediated by the dipole-dipole coupling between the donor and acceptor materials, can survive up to several tens of nm. In this talk, I would like to present our recent studies to understand the effect of energy bands overlap in the ET process in TMD HSs. First, we showed that in the type-II HSs formed using the 1Ls of molybdenum diselenide (MoSe2) and rhenium disulfide (ReS2), an ET process dominates over the fast CT process, resulting 360% photoluminescence (PL) enhancement in the HS area. After completely blocking the CT process, this enhancement increased further up to more than 1 order of magnitude higher. Next, we showed that HS formed between the 1Ls of molybdenum disulfide (MoS2) and tungsten disulfide (WSe2), an unusual ET process occur from the lower bandgap WSe2 to higher bandgap MoS2 due to the resonant overlaps between the high-lying excitonic states. These works will help us to realize the complex ET processes in TMD HSs for better development of the TMD-based novel optoelectronic device applications.

Keywords: Excitons; Energy Transfer; TMDC; van der Waals heterostructures