The integration of electronic and photonic chips hinges on the availability of efficient light sources and modulators that are compatible with on-chip interconnects. Among these, mid-infrared (mid-IR) emitters are especially critical, as they enable low-loss transmission through atmospheric windows and unlock powerful capabilities for molecular fingerprinting and chemical sensing. In this study, we demonstrate that 2D tellurium (Te) nanoflakes can serve as highly efficient, electrically tunable, and linearly polarized mid-IR emitters. Leveraging the narrow direct bandgap (≈0.36 eV) and anisotropic crystal symmetry of Te nanoflakes, we achieve electrically tunable mid-IR photoluminescence (PL) with near-complete PL intensity modulation, a stable emission wavelength (≈3.4 µm), and near-perfect linear polarization. In addition, we demonstrate a dual-gate device that allows independent control of the electrostatic doping and vertical electric field, and further theoretical analysis reveals that the electrical tunability of the PL intensity originates primarily from the gate-controlled carrier density. Building on this robust control, we demonstrate high-speed electro-optical switches and programmable logic gates for on-chip encryption, underscoring the excellent compatibility of Te with advanced optoelectronic circuits. Collectively, these advances establish Te as a cornerstone material for hybrid electronic-photonic systems, directly addressing the urgent demand for mid-IR components in next-generation optical interconnects.
As a fundamental structural feature, the symmetry of materials determines the exotic quantum properties in transition metal dichalcogenides (TMDs) with charge density waves (CDWs). The Janus structure, an artificially constructed lattice, provides an opportunity to tune the electronic structures and their associated behavior, such as CDW states. However, limited by the difficulties in atomic-level fabrication and material stability, the experimental visualization of the CDW states in two-dimensional (2D) TMDs with Janus structure is still rare. Here, using surface selenization of VTe2, we fabricated monolayer Janus VTeSe. With scanning tunneling microscopy, we observed and characterized an unusual sqrt13 x sqrt13 CDW state with threefold rotational symmetry breaking. Combined with theoretical calculations, we find that this CDW state can be attributed to the magnetic-involved charge modulation in the Janus VTeSe, rather than the conventional electron-phonon coupling. Our findings provide a promising platform for studying the CDW states and artificially tuning the electronic properties of the 2D TMDs toward the related fundamental and applied studies.
Yating Li, Mengmeng Niu, Junpeng Zeng, Quan Zhou, Xu Wu, Wei Ji, Yeliang Wang, Ren Zhu, Jingsi Qiao, Jianbin Xu, Yi Shi, Xinran Wang, and Daowei He
Abstract:
Organic semiconductors are highly promising as channel materials for energy-efficient, cost-effective, and flexible electronics. However, grain boundaries (GBs) can cause significant device performance variation, posing a major challenge for the development of high-performance organic circuits. In this work, we effectively passivated GB-induced traps in monolayer organic thin-film transistors (OTFTs) via p-type doping with the organic salt TrTPFB. The doping strategy broadens the mobility edge, effectively shielding GB-induced energy barriers and Coulomb scattering, and promotes deeper nonlocalized hybridization states for conduction. Consequently, the charge transport mechanism transitions from multiple trapping and release (MTR) to a more band-like behavior, even when GBs are present within the device channel. The doped OTFTs demonstrate ultralow mobility variation (1.4%) and threshold voltage variation (4.9%), as well as record-low contact resistant of RC = 0.6 Ω·cm, outperforming most single-crystal technologies. These performance metrics render doped monolayer polycrystalline films highly promising candidates for industrial-scale organic electronics.
Qingyang Wang, Mengmeng Niu, Weikang Zhou, Yicheng Ma, Chun Huang, Gege Yang, Yan Shao, Xu Wu, Cong Wang, Wei Ji*, Yeliang Wang*, Jingsi Qiao*
Abstract:
Two-dimensional (2D) multiferroic materials have significant application potential for novel storage devices due to their tunable magnetic and ferroelectric properties. Transition metal phosphorus chalcogenides MPX3 (X = S, Se, and Te) were found to be magnetic and multiferroic with excellent tunability, promising for multifunctionalized applications. In this study, we investigated the antiferromagnetic and antiferroelectric properties of two-dimensional FePX3 and CuFeP2X6 by density functional theory. Monolayer FePS3/FePSe3 and FePTe3 take intralayer zigzag and Neel antiferromagnetic ground states, respectively. This tunability of intralayer magnetism results from the competition between the spin-exchange interactions of the first and second nearest Fe atoms. Bilayer FePX3 shows weak interlayer interactions and keeps electronic and magnetic characteristics similar to those of the monolayer. Moreover, by introducing the nonmagnetic Cu atom into FePX3, the inversion symmetry broken induces CuFeP2X6 to be multiferroic materials. The transition barrier between ferroelectric (FE) and antiferroelectric (AFE) phases in CuFeP2S6 and CuFeP2Se6 is 0.09 and 0.04 eV/f.u., similar to well-known multiferroic CuCrP2S6. FE-to-AFE phase transition is expected to be achieved by applying an electric field and uniaxial strain. CuFeP2Te6 shows the ground state with a distorted paraelectric phase. Our results show the fundamental properties and in-depth understanding of 2D FePX3 and CuFeP2X6, guiding further investigation of 2D multifunctionalized magnetoelectric devices.
Xuanhao Wu, Mengmeng Niu, Xin Tian, Xiaoyan Peng, Pio John S. Buenconsej, Xu Wu, Yeliang Wang, Wei Ji, Yi Li, Jingsi Qiao,Jifang Tao, Mingming Zhang, Song Xiaof and Hongye Yuan
Abstract:
Developing sensitive metal–organic framework (MOF) systems to overcome the ubiquitous trade-off between porosity and conductivity remains a formidable yet sought-after endeavor. This pursuit is of great significance for the development of MOF-based chemiresistive sensors with enhanced sensitivity and selectivity. Herein, we present an innovative template assisted strategy that utilizes the two-dimensional properties and good conductivity of MXene nanosheets, as well as lattice matching between MXene (Nb2C) and selected Ni3(HITP)2, to achieve controllable self-assembly of Ni3(HITP)2 on MXene sheets. This results in Ni3(HITP)2/MXene (HITP: 2,3,6,7,10,11-hexaaminotriphenylene) heterostructures with considerable conductivity, porosity, and solution processability. The powder and film electrical conductivity are 4.8 × 103 and 5.3 × 105 S m−1, respectively, and the BET specific surface area can reach 797.8 m2 g−1. It is worth noting that excellent solution processability helps to prepare large-area films (23 cm × 9 cm) with good uniformity. Gas sensors based on Ni3(HITP)2/MXene heterostructures exhibit high sensitivity (LOD ∼ 5 ppb) and selectivity towards ultratrace ethanol at room temperature, setting a new benchmark. Such sensing behavior stems from the strong coupling of Ni3(HITP)2/MXene heterostructures and their enhanced interaction with ethanol, evidenced by experimental results and theoretical calculations. Real-time respiratory sensing assessments underscore their practicality in healthcare monitoring. This straightforward approach simplifies the integration of MOF-related materials on miniaturized devices with outstanding performance.
