Ultrafast Electronic Dynamics in Anisotropic Indirect Interlayer Excitonic States of Monolayer WSe2/ReS2 Heterojunctions

Yulu Qin; Rui Wang; Xiaoyuan Wu; Yunkun Wang; Xiaofang Li; Yunan Gao; Liangyou Peng; Qihuang Gong; Yunquan Liu

doi:10.1021/acs.nanolett.3c02488

Ultrafast Electronic Dynamics in Anisotropic Indirect Interlayer Excitonic States of Monolayer WSe₂/ReS₂ Heterojunctions

Nano Lett. 2023 Sep 27;23(18):8643-8649. doi: 10.1021/acs.nanolett.3c02488. Epub 2023 Sep 6.

Authors

Yulu Qin¹, Rui Wang¹, Xiaoyuan Wu¹, Yunkun Wang¹, Xiaofang Li¹, Yunan Gao¹, Liangyou Peng¹, Qihuang Gong^{1

2

3}, Yunquan Liu^{1

2

3}

Affiliations

¹ State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-Optoelectronics, School of Physics, Peking University, Beijing 100871, China.
² Peking University Yangtze Delta Institute of Optoelectronics, Nantong, Jiangsu 226010, China.
³ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.

PMID: 37672749
DOI: 10.1021/acs.nanolett.3c02488

Abstract

Understanding ultrafast electronic dynamics of the interlayer excitonic states in atomically thin transition metal dichalcogenides is of importance in engineering valleytronics and developing excitonic integrated circuits. In this work, we experimentally explored the ultrafast dynamics of indirect interlayer excitonic states in monolayer type II WSe₂/ReS₂ heterojunctions using time-resolved photoemission electron microscopy, which reveals its anisotropic behavior. The ultrafast cooling and decay of excited-state electrons exhibit significant linear dichroism. The ab initio theoretical calculations provide unambiguous evidence that this linear dichroism result is primarily associated with the anisotropic nonradiative recombination of indirect interlayer excitonic states. Measuring time-resolved photoemission energy spectra, we have further revealed the ultrafast evolution of excited-state electrons in anisotropic indirect interlayer excitonic states. The findings have important implications for controlling the interlayer moiré excitonic effects and designing anisotropic optoelectronic devices.

Keywords: Anisotropic interlayer excitonic states; First-principles calculations; Polarization-controllable; Spatiotemporal imaging; Transition metal dichalcogenides.