Excitation-Dependent High-Lying Excitonic Exchange via Interlayer Energy Transfer from Lower- to- Higher Bandgap 2D Material

Arka Karmakar; Tomasz Kazimierczuk; Igor Antoniazzi; Mateusz Raczyński; Suji Park; Houk Jang; Takashi Taniguchi; Kenji Watanabe; Adam Babiński; Abdullah Al-Mahboob; Maciej R Molas

doi:10.1021/acs.nanolett.3c01127

Excitation-Dependent High-Lying Excitonic Exchange via Interlayer Energy Transfer from Lower- to- Higher Bandgap 2D Material

Nano Lett. 2023 Jun 28;23(12):5617-5624. doi: 10.1021/acs.nanolett.3c01127. Epub 2023 Jun 8.

Affiliations

¹ Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
² Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, USA.
³ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
⁴ Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.

Abstract

High light absorption (∼15%) and strong photoluminescence (PL) emission in monolayer (1L) transition metal dichalcogenides (TMDs) make them ideal candidates for optoelectronic device applications. Competing interlayer charge transfer (CT) and energy transfer (ET) processes control the photocarrier relaxation pathways in TMD heterostructures (HSs). In TMDs, long-distance ET can survive up to several tens of nm, unlike the CT process. Our experiment shows that an efficient ET occurs from the 1Ls WSe₂-to-MoS₂ with an interlayer hexagonal boron nitride (hBN), due to the resonant overlapping of the high-lying excitonic states between the two TMDs, resulting in enhanced HS MoS₂ PL emission. This type of unconventional ET from the lower-to-higher optical bandgap material is not typical in the TMD HSs. With increasing temperature, the ET process becomes weaker due to the increased electron-phonon scattering, destroying the enhanced MoS₂ emission. Our work provides new insight into the long-distance ET process and its effect on the photocarrier relaxation pathways.

Keywords: 2D material; MoS2; WSe2; band-nesting; energy transfer; heterostructure.