Article
Chemistry, Multidisciplinary
Leo Yu, Minda Deng, Jingyuan Linda Zhang, Sven Borghardt, Beata Kardynal, Jelena Vuckovic, Tony F. Heinz
Summary: Atomically thin semiconductors offer an attractive platform for quantum emitters, although reported quantum emitters in these materials have relied on spin-forbidden transitions. By employing strain confinement in monolayer MoSe2, engineered quantum emitters with radiative rates exceeding those of other solid-state systems have been produced.
Review
Nanoscience & Nanotechnology
Emma C. Regan, Danqing Wang, Eunice Y. Paik, Yongxin Zeng, Long Zhang, Jihang Zhu, Allan H. MacDonald, Hui Deng, Feng Wang
Summary: This Review discusses two approaches for realizing emergent excitonic physics in two-dimensional semiconductor heterostructures: the introduction of a moire superlattice and the formation of an optical cavity.
NATURE REVIEWS MATERIALS
(2022)
Article
Chemistry, Physical
Adlen Smiri, Thierry Amand, Sihem Jaziri
Summary: Strain-induced two-dimensional transition metal dichalcogenide forms localized states with exciting band gap properties on hBN substrate, making it a good candidate for single-photon sources. Numerical simulations show that a single optically active confined exciton state exists in MoS2/hBN nanobubbles.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
A. C. Dias, Helena Braganca, Joao Paulo A. de Mendonca, Juarez L. F. Da Silva
Summary: In this study, 72 2D monolayers from transition-metal dichalcogenides were screened for high-performance photovoltaic devices. Theoretical and experimental analyses were conducted on the electronic, optical, and excitonic properties, revealing nontrivial correlations. The presence of excitons in stable semiconductors affects band alignment and power conversion efficiency in photovoltaic devices.
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Daniel Hernangomez-Perez, Amir Kleiner, Sivan Refaely-Abramson
Summary: In this study, the effect of defects on the electronic and optical properties of WS2-graphene and MoS2-graphene van der Waals heterobilayers was investigated using many-body perturbation theory. It was found that chalcogen defects and the graphene interface significantly alter the optical properties of the transition-metal dichalcogenide in the heterobilayer. The introduction of defects leads to low-energy optical transitions and excitons with non-negligible oscillator strength, while decreasing the optical response of the pristine-like transition-metal dichalcogenide intralayer excitons. These findings provide insights into interface design for defect engineering in photovoltaic and transport applications.
Article
Materials Science, Multidisciplinary
Ilya A. Eliseyev, Aidar I. Galimov, Maxim. V. Rakhlin, Evgenii A. Evropeitsev, Alexey A. Toropov, Valery Yu. Davydov, Sebastian Thiele, Joerg Pezoldt, Tatiana V. Shubina
Summary: This study focused on time-resolved microphotoluminescence in MoS2 monolayers and bilayers, revealing the significant impact of strain on the exciton spectrum and highlighting the necessity to consider it for achieving desired optical properties of 2D MoS2.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Xiongli Wu, Xuejun Zheng, Guangbiao Zhang, Xinnan Chen, Jianwen Ding
Summary: After gamma-ray irradiation treatment, monolayer tungsten diselenide can transition into an n-doped semiconductor, which opens up potential electronic property engineering applications.
Article
Nanoscience & Nanotechnology
Erik G. C. P. van Loon, Malte Schueler, Daniel Springer, Giorgio Sangiovanni, Jan M. M. Tomczak, Tim O. O. Wehling
Summary: Two-dimensional materials are influenced by their surroundings, and manipulating the dielectric screening can directly control the insulating state of Mott materials. Many-body calculations show spectroscopic changes and an insulator-to-metal transition through Coulomb engineering. We discuss the experimental conditions for achieving Coulomb engineering of Mott materials based on our proof-of-principle calculations.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Multidisciplinary Sciences
Elyse Barre, Ouri Karni, Erfu Liu, Aidan L. O'Beirne, Xueqi Chen, Henrique B. Ribeiro, Leo Yu, Bumho Kim, Kenji Watanabe, Takashi Taniguchi, Katayun Barmak, Chun Hung Lui, Sivan Refaely-Abramson, Felipe H. da Jornada, Tony F. Heinz
Summary: Interlayer excitons, electron-hole pairs bound across two monolayer van der Waals semiconductors, offer promising electrical tunability and localizability. The dielectric response of interlayer excitons was directly measured using their static electric dipole moment, and an intrinsic radiative lifetime and transition characteristics were determined. This study identifies a momentum-indirect emission mechanism and emphasizes the importance of characterizing absorption for applications relying on light-matter interactions.
Review
Chemistry, Multidisciplinary
Yuanda Liu, Ahmed Elbanna, Weibo Gao, Jisheng Pan, Zexiang Shen, Jinghua Teng
Summary: This article presents a general view of interlayer excitons in 2D van der Waals heterostructures and the state-of-the-art developments. By employing staggered type-II band alignment, the interlayer direct bandgap can be expanded, enabling exciton devices at room temperature and observation of quantum behaviors.
ADVANCED MATERIALS
(2022)
Review
Materials Science, Multidisciplinary
Kha Tran, Junho Choi, Akshay Singh
Summary: Fabricating van der Waals bilayer heterostructures provides a unique physical system with rich electronic and optical properties by stacking two-dimensional layers. The twist-angle between component layers is a key parameter that can control the period of lateral confinement and the nature of excitons, leading to the creation of exotic physical states. This review article focuses on the opto-electronic properties of excitons in transition metal dichalcogenide semiconductor twisted bilayer heterostructures, providing insights into moire excitons and nanoscale mapping of moire superlattice.
Article
Nanoscience & Nanotechnology
Aanchal Alagh, Fatima Ezahra Annanouch, Ayrton Sierra-Castillo, Emile Haye, Jean-Francois Colomer, Eduard Llobet
Summary: In this study, a chemoresistive-type gas sensor composed of two-dimensional WSe2 was fabricated for the first time. The sensor showed dual selectivity towards NH3 and NO2 gases, with the selectivity tunable by adjusting the operating temperature. At moderate temperatures, the sensor exhibited stable and reproducible responses towards NH3 vapor detection, and high sensitivity towards NO2 molecules even at room temperature. The sensor also demonstrated high resilience against ambient humidity, making it suitable for NH3 gas detection in various environments.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Yaroslav Zhumagulov, Alexei Vagov, Dmitry R. Gulevich, Vasili Perebeinos
Summary: Charged excitons or trions play a crucial role in the optical spectra of low-dimensional doped monolayers of TMDC. By diagonalizing the three-body Hamiltonian, the study investigates the low-lying trion states in four types of TMDC monolayers and explores the influence of doping and dielectric environment on their fine structure.
Article
Chemistry, Physical
Yusheng Hou, Feng Xue, Liang Qiu, Zhe Wang, Ruqian Wu
Summary: Two-dimensional van der Waals Janus materials and their heterostructures have the potential to design various functionalities. In this study, high T-C ferromagnetic semiconductors with out-of-plane magnetization were found in CrSX (X = Cl, Br, I) through systematic first-principles studies. Furthermore, large-gap quantum anomalous Hall effect and sizable valley splitting can be achieved in van der Waals heterostructures CrSBr/Bi2Se3/CrSBr and MoTe2/CrSBr, respectively, through the magnetic proximity effect. Additionally, skyrmion states were observed in CrTeX (X = Cl, Br, I) under external magnetic fields due to large Dzyaloshinskii-Moriya interactions. The multifunctionalities of two-dimensional Janus magnet Cr-based dichalcogenide halides in topological electronic and valleytronic devices were demonstrated.
NPJ COMPUTATIONAL MATERIALS
(2022)
Retraction
Chemistry, Multidisciplinary
Bhaskar Kaviraj, Dhirendra Sahoo
Summary: The paper on the physics of excitons and their transport in two dimensional transition metal dichalcogenide semiconductors by Bhaskar Kaviraj and Dhirendra Sahoo, published in RSC Adv. in 2019, has been retracted.
Article
Engineering, Mechanical
Hui Zhao, Jiao Wang, Chenchen Wang, Lei Zheng, Zhipeng Li, Tianhui Ren
Summary: In this study, three environmentally friendly sulfur- and phosphorus-free organic molybdenums with different structures were prepared, and the relationship between molecular structure and tribological properties was investigated. The synergistic effect on antiwear and antifriction properties after compounding with conventional zinc dialkyldithiophosphate (ZDDP) was also studied. It was found that the different compounds exhibited different levels of synergistic effect. In-depth surface and cross-sectional analyses revealed that the formation of a homogeneous and compact tribofilm contributed to the excellent synergistic effect.
TRIBOLOGY INTERNATIONAL
(2023)
Article
Chemistry, Multidisciplinary
Shayan Louie, Yu Zhong, Si Tong Bao, Cedric Schaack, Alvaro Montoya, Zexin Jin, Nicholas M. Orchanian, Yang Liu, Wenrui Lei, Kelsey Harrison, James Hone, Alexander Angerhofer, Austin M. Evans, Colin P. Nuckolls
Summary: This study describes the synthesis of hexameric macrocyclic aniline (MA[6]) and its assembly into conductive organic wires. The electrical conductivity of ESMA[6] is high and responsive to acid-base conditions. The crystal structure of ES-MA[6] reveals the formation of trimeric units and nanotubes with regular channels, providing a potential route for synthetic nanotubes used in ion or small molecule transport. Spectroscopic analysis further demonstrates the interconversion between acidic and basic forms of the macrocycles and how charge carriers are formed through protonation, resulting in high electrical conductivity.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Arnab Barman Ray, Arunabh Mukherjee, Liangyu Qiu, Renee Sailus, Sefaattin Tongay, Anthony Nickolas Vamivakas
Summary: This study investigates the Moiré heterobilayers and reveals the trapped interlayer excitons in this structure. It explains the characteristic blueshift in photoluminescence (PL) with increasing carrier density and finds a significant difference in interlayer exciton-trion conversion efficiency compared to conventional intralayer species. The absence of optical generation of trions in these materials is attributed to the highly localized, near subnanometer confinement of trapped species in the Moiré potentials.
Article
Chemistry, Physical
Brian S. Y. Kim, Aaron J. Sternbach, Min Sup Choi, Zhiyuan Sun, Francesco L. Ruta, Yinming Shao, Alexander S. McLeod, Lin Xiong, Yinan Dong, Ted S. Chung, Anjaly Rajendran, Song Liu, Ankur Nipane, Sang Hoon Chae, Amirali Zangiabadi, Xiaodong Xu, Andrew J. Millis, P. James Schuck, Cory. R. Dean, James C. Hone, D. N. Basov
Summary: Researchers have demonstrated a charge transfer strategy to program ambipolar low-loss graphene plasmonic structures, by covering graphene with transition-metal dichalcogenides and subsequently oxidizing them into transition-metal oxides. They achieve ambipolar low-loss plasmon polaritons at the transition-metal-oxide/graphene interfaces and precisely control the electron and hole densities induced by oxidation-activated charge transfer with the help of dielectric van der Waals spacers.
Article
Physics, Multidisciplinary
Erin Morissette, Jiang-Xiazi Lin, Dihao Sun, Liangji Zhang, Song Liu, Daniel Rhodes, Kenji Watanabe, Takashi Taniguchi, James Hone, Johannes Pollanen, Mathias S. Scheurer, Michael Lilly, Andrew Mounce, J. I. A. Li
Summary: Phase transitions in twisted bilayer graphene allow for the characterization of spin and valley couplings, and the observation of collective excitations. These excitations provide information about the electronic order in strongly correlated systems. By using a resistively detected electron spin resonance technique, low-energy collective excitations have been observed near the magic angle. The resonance response is dependent on the strong correlations within the flat moire energy band.
Article
Multidisciplinary Sciences
Richen Xiong, Jacob H. Nie, Samuel L. Brantly, Patrick Hays, Renee Sailus, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, Chenhao Jin
Summary: We observe a bosonic correlated insulator composed of excitons in tungsten diselenide/tungsten disulfide (WSe2/WS2) moire superlattices. The insulator transitions continuously into an electron correlated insulator with varying charge density, suggesting a mixed correlated insulating state between the two limits.
Article
Multidisciplinary Sciences
Naim Hossain Patoary, Jing Xie, Guantong Zhou, Fahad Al Mamun, Mohammed Sayyad, Sefaattin Tongay, Ivan Sanchez Esqueda
Summary: This paper presents a comprehensive experimental analysis on the improvements of two-dimensional p-type metal-oxide-semiconductor field effect transistors (PMOS FETs) using pure van der Waals contacts and high-k metal gate stacks on few-layer tungsten diselenide. The study shows that standard metallization techniques result in significant Fermi-level pinning, but using high work function metals like Pt or Pd can reduce the Schottky barrier heights. Temperature-dependent analysis reveals that contact resistance is mainly contributed by the channel access region, and less damaging metallization techniques combined with strongly scaled high-k metal gate stacks can significantly improve contact resistance.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Multidisciplinary
Shan-Wen Cheng, Ding Xu, Haowen Su, James M. Baxter, Luke N. Holtzman, Kenji Watanabe, Takashi Taniguchi, James C. Hone, Katayun Barmak, Milan Delor
Summary: In this study, we use excitons in two-dimensional materials as sensors to achieve visible-light imaging of phonon polariton propagation in hexagonal boron nitride, and observe the phenomenon of co-propagation of excitons and phonon polaritons. This research provides a new method for high-precision imaging of polar excitations and a new mechanism for realizing ballistic exciton transport at room temperature.
Editorial Material
Chemistry, Physical
Yang Liu, James C. Hone
Article
Chemistry, Physical
Weijie Li, Zach Hadjri, Luka M. Devenica, Jin Zhang, Song Liu, James Hone, Kenji Watanabe, Takashi Taniguchi, Angel Rubio, Ajit Srivastava
Summary: By using a WS2/WSe2/WS2 heterotrilayer, this study creates a quantum superposition of quadrupolar excitons and reveals the mechanism of this phase transition under different electric field conditions. The results demonstrate that van der Waals heterotrilayers can be used to engineer light-matter interactions and explore quantum phase transitions between many-exciton phases.
Article
Multidisciplinary Sciences
Zhen Lian, Dongxue Chen, Yuze Meng, Xiaotong Chen, Ying Su, Rounak Banerjee, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi
Summary: By applying an electric field, the authors are able to manipulate the superposition between two moire sites in the trilayer WSe2 and monolayer WS2 system through hybridization with intralayer excitons. Moire superlattices of semiconducting transition metal dichalcogenides allow for unprecedented control of electron wavefunctions, leading to the emergence of quantum states.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Zhen Lian, Dongxue Chen, Lei Ma, Yuze Meng, Ying Su, Li Yan, Xiong Huang, Qiran Wu, Xinyue Chen, Mark Blei, Takashi Taniguchi, Kenji Watanabe, Sefaattin Tongay, Chuanwei Zhang, Yong-Tao Cui, Su-Fei Shi
Summary: The authors observe quadrupolar excitons in a WSe2-WS2-WSe2 trilayer moire superlattice, resulting from the hybridization of WSe2 valence moire flatbands. They also reveal a hybridized interlayer Mott insulator state by electrostatic gating, in which holes are shared between the two WSe2 layers but confined laterally in moire superlattices. The study demonstrates the potential of trilayer moire systems for realizing novel correlated states and engineering quantum phase transitions.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Marko M. Petric, Viviana Villafane, Paul Herrmann, Amine Ben Mhenni, Ying Qin, Yasir Sayyad, Yuxia Shen, Sefaattin Tongay, Kai Mueller, Giancarlo Soavi, Jonathan J. Finley, Matteo Barbone
Summary: This study investigates the second and third harmonic generation in Janus monolayers of MoSSe and WSSe. The full second-order susceptibility tensor of MoSSe, including its out-of-plane components, is mapped using polarization-resolved spectroscopy. The effective third-order susceptibility and second-order nonlinear dispersion close to exciton resonances are also measured for both MoSSe and WSSe at different temperatures. This work provides a foundation for understanding the nonlinear optical properties of Janus transition metal dichalcogenides and exploring their use in future on-chip multifaceted photonic devices.
ADVANCED OPTICAL MATERIALS
(2023)
Review
Chemistry, Physical
Xiaole Zhang, Tianhui Ren, Zhipeng Li
Summary: Two-dimensional (2D) nanomaterial lubricants are gaining attention due to their potential as mild and environmentally friendly anti-wear agents, alleviating energy loss and resource waste caused by mechanical wear. The development of diverse 2D nanomaterials in lubrication has exponentially increased since the discovery of graphene in 2004. This review focuses on the research progress in the development of 2D nanomaterials as lubricating materials and their role in friction systems, including advanced 2D lubricants, strategies to enhance tribological properties, and applications in lubricating systems. The challenges and future strategies in this research field are also discussed.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)