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1. Broken mirror symmetry in excitonic response of reconstructed domains in twisted MoSe2/MoSe2 bilayers

   https://doi.org/10.1038/s41565-020-0728-z  

   Sung, Jiho; Zhou, You; Scuri, Giovanni; Zólyomi, Viktor; Andersen, Trond I.; Yoo, Hyobin; Wild, Dominik S.; Joe, Andrew Y.; Gelly, Ryan J.; Heo, Hoseok; et al (September 2020, Nature Nanotechnology)

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2. Moiré trions in MoSe2/WSe2 heterobilayers

   https://doi.org/10.1038/s41565-021-00969-2  

   Wang, Xi; Zhu, Jiayi; Seyler, Kyle L.; Rivera, Pasqual; Zheng, Huiyuan; Wang, Yingqi; He, Minhao; Taniguchi, Takashi; Watanabe, Kenji; Yan, Jiaqiang; et al (September 2021, Nature Nanotechnology)

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3. Signatures of moiré trions in WSe2/MoSe2 heterobilayers

   https://doi.org/10.1038/s41586-021-03541-z  

   Liu, Erfu; Barré, Elyse; van Baren, Jeremiah; Wilson, Matthew; Taniguchi, Takashi; Watanabe, Kenji; Cui, Yong-Tao; Gabor, Nathaniel M.; Heinz, Tony F.; Chang, Yia-Chung; et al (June 2021, Nature)

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4. Exciton-polaron Rydberg states in monolayer MoSe2 and WSe2

   https://doi.org/10.1038/s41467-021-26304-w  

   Liu, Erfu; van Baren, Jeremiah; Lu, Zhengguang; Taniguchi, Takashi; Watanabe, Kenji; Smirnov, Dmitry; Chang, Yia-Chung; Lui, Chun Hung (October 2021, Nature Communications)

   Abstract Exciton polaron is a hypothetical many-body quasiparticle that involves an exciton dressed with a polarized electron-hole cloud in the Fermi sea. It has been evoked to explain the excitonic spectra of charged monolayer transition metal dichalcogenides, but the studies were limited to the ground state. Here we measure the reflection and photoluminescence of monolayer MoSe₂and WSe₂gating devices encapsulated by boron nitride. We observe gate-tunable exciton polarons associated with the 1 s–3 s exciton Rydberg states. The ground and excited exciton polarons exhibit comparable energy redshift (15~30 meV) from their respective bare excitons. The robust excited states contradict the trion picture because the trions are expected to dissociate in the excited states. When the Fermi sea expands, we observe increasingly severe suppression and steep energy shift from low to high exciton-polaron Rydberg states. Their gate-dependent energy shifts go beyond the trion description but match our exciton-polaron theory. Our experiment and theory demonstrate the exciton-polaron nature of both the ground and excited excitonic states in charged monolayer MoSe₂and WSe₂. 

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5. Photoswitchable optoelectronic properties of 2D MoSe2/diarylethene hybrid structures

   https://doi.org/10.1038/s41598-024-57479-z  

   Park, Sewon; Ji, Jaehoon; Cunningham, Connor; Pillai, Srajan; Rouillon, Jean; Benitez-Martin, Carlos; Fang, Mengqi; Yang, Eui-Hyeok; Andréasson, Joakim; You, Jeong Ho; et al (March 2024, Scientific Reports)

   Abstract The ability to modulate optical and electrical properties of two-dimensional (2D) semiconductors has sparked considerable interest in transition metal dichalcogenides (TMDs). Herein, we introduce a facile strategy for modulating optoelectronic properties of monolayer MoSe₂with external light. Photochromic diarylethene (DAE) molecules formed a 2-nm-thick uniform layer on MoSe₂, switching between its closed- and open-form isomers under UV and visible irradiation, respectively. We have discovered that the closed DAE conformation under UV has its lowest unoccupied molecular orbital energy level lower than the conduction band minimum of MoSe₂, which facilitates photoinduced charge separation at the hybrid interface and quenches photoluminescence (PL) from monolayer flakes. In contrast, open isomers under visible light prevent photoexcited electron transfer from MoSe₂to DAE, thus retaining PL emission properties. Alternating UV and visible light repeatedly show a dynamic modulation of optoelectronic signatures of MoSe₂. Conductive atomic force microscopy and Kelvin probe force microscopy also reveal an increase in conductivity and work function of MoSe₂/DAE with photoswitched closed-form DAE. These results may open new opportunities for designing new phototransistors and other 2D optoelectronic devices. 

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