Entropy engineering has emerged as a promising paradigm for tailoring the electronic and photoelectric properties of materials. Although high-entropy transition metal sulfides have been achieved, entropy engineering in two-dimensional (2D) tellurides remains challenging. In this work, we report the successful synthesis of a 1T' monolayer heptanary medium-entropy (ME) alloy (Mo_aW_bFe_cCo_dS_xSe_yTe_z) via a one-step chemical vapor deposition method. Advanced characterizations, including scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, and electron energy loss spectroscopy confirm the uniform atomic-level distribution of the seven constituent elements within the alloy. The 1T' ME alloy device exhibits a high drain current of ~ 6.5 mA, which is 216 times higher than the ~ 30 μA observed in pristine 1T' MoTe₂. Furthermore, the 1T' ME alloy photodetector exhibits responsivities of 27.92 A/W at 1064 nm and 63.74 A/W at 1550 nm, outperforming those of the pristine 1T' MoTe₂ by more than two orders of magnitude. This remarkable enhancement is attributed to the reduced Schottky barrier (15.9 meV) at the 1T' ME alloy/electrode interface, along with the enhanced conductance (0.43 S) and reduced thermal activation energy (4.1 meV) in the 1T' ME alloy, collectively facilitating more efficient carrier injection and transport. Our work provides a distinct pathway for tailoring the properties of transition metal dichalcogenides through entropy engineering and offers valuable insights for the design of high-performance infrared photodetectors.

Two-dimensional (2D) materials as channel materials provide a promising alternative route for future electronics and flexible electronics, but the device performance is affected by the quality of interface between the 2D-material channel and the gate dielectric. Here we demonstrate an indium selenide (InSe)/hexagonal boron nitride (hBN)/graphite heterostructure as a 2D field-effect transistor (FET), with InSe as channel material, hBN as dielectric, and graphite as gate. The fabricated FETs feature high electron mobility up to 1,146 cm²·V^-1·s^-1 at room temperature and on/off ratio up to 10¹⁰ due to the atomically flat gate dielectric. Integrated digital inverters based on InSe/hBN/graphite heterostructures are constructed by local gating modulation and an ultrahigh voltage gain up to 93.4 is obtained. Taking advantages of the mechanical flexibility of these materials, we integrated the heterostructured InSe FET on a flexible substrate, exhibiting little modification of device performance at a high strain level of up to 2%. Such high-performance heterostructured device configuration based on 2D materials provides a new way for future electronics and flexible electronics.

We use Z-contrast imaging and atomically resolved electron energy-loss spectroscopy on an aberration-corrected scanning transmission electron microscope to investigate the local electronic states of boron atoms at different edge structures in monolayer and bilayer hexagonal boron nitride (h-BN). We find that edges with bonding unsaturated sp² boron atoms have a unique spectroscopic signature with a prominent pre-peak at ~ 190.2 eV in the B K-edge fine structure. First-principles calculations reveal that the observed pre-peak arises from excitations to the in-plane lowest-energy empty sp² boron dangling bonds at the B-terminated edge. This spectroscopic signature can serve as a fingerprint to explore new edge structures in h-BN.