Synthesis of Ultrathin 2D Nonlayered α‐MnSe Nanosheets, MnSe/WS₂ Heterojunction for High‐Performance Photodetectors

Abstract

Numerous efforts have been made to synthesize 2D atomic semiconductor materials and their heterojunctions because of the diverse novel properties and potential applications in constructing next‐generation highly compact electronic and optoelectronic devices. However, intrinsic 2D p‐type semiconductor materials are still scarce. Herein, to enrich the p‐type 2D semiconductor family, epitaxial growth of a large‐area, ultrathin 2D nonlayered p‐type semiconductor α‐MnSe on mica with the thickness down to one unit crystal cell (0.9 nm) is reported. Moreover, the thickness of the α‐MnSe nanosheets can be systematically tailored from over 150 to 0.9 nm by increasing the flow rate of the carrier gas. X‐ray‐diffraction, transmission electron microscopy, and electron diffraction studies confirm that the resulting 2D nanosheets are high‐quality single crystals. The photodetector based on the p‐type α‐MnSe nanosheet shows a fast response time of 4 ms. Furthermore, α‐MnSe/WS2 heterojunctions are synthesized and a diode based on p‐type α‐MnSe and n‐type WS2 displays outstanding photodetectivity (1.00 × 1013 Jones), high photoresponsivity (49.1 A W−1), and an obvious rectification ratio (283). Together, the synthesis of α‐MnSe and the α‐MnSe/WS2 p–n heterojunction provides opportunities for next‐generation electronics and optoelectronics.

Mo2N–W2N Heterostructures Embedded in Spherical Carbon Superstructure as Highly Efficient Polysulfide Electrocatalysts for Stable Room‐Temperature Na–S Batteries

“…One can expect that rational designing transition-metal-nitride-based heterostructures confined in carbon host for RT Na-S batteries can significantly improve the utilization of S, enhance the reaction kinetics, and restrain the polysulfide shuttle process. [35,36] In addition, there are a few investigations on electrochemical reaction mechanism of sulfur cathodes in RT Na-S batteries.…”

Highly Efficient Full van der Waals 1D p‐Te/2D n‐Bi2O2Se Heterodiodes with Nanoscale Ultra‐Photosensitive Channels

“…According to the sectional profile of V CPD , the V CPD difference of the Te/Bi 2 O 2 Se heterojunction is calculated to be around 30 mV (Figure 4c). In addition, as characterized by ultraviolet photoelectron spectroscopy (UPS) of Bi 2 O 2 Se NSs [10] Sb 2 Se 3 /WS 2 , [8b] AsP/InSe, [19b] InSe/PdSe 2 , [22] GaSe/VO 2 , [24] Te/MoS 2 , [25] MnSe/WS 2 , [26] Bi 2 O 2 Se, [27] Se/ReS 2 , [28] PtS 2 /WSe 2 , [29] and Te/WS 2 . [30] (Figure 4d Combining the above analysis and further taking the bandgap of thin Bi 2 O 2 Se NSs and Te NWs to be 0.8 eV [32b,40] and 0.35 eV, respectively, [35,41] we construct a type II band alignment before contact in Figure 4e .…”

“…e) Responsivity and f) detectivity of the device under varying light intensities at V ds = −100 mV under laser illumination of 635, 532, and 405 nm, respectively. g) Responsivity, detectivity, and h) rise and decay time of typical state-ofthe-art low-dimensional semiconductor-based photodetectors reported in literature including Te/ReS 2 ,[10] Sb 2 Se 3 /WS 2 ,[8b] AsP/InSe,[19b] InSe/PdSe 2 ,[22] GaSe/VO 2 ,[24] Te/MoS 2 ,[25] MnSe/WS 2 ,[26] Bi 2 O 2 Se,[27] Se/ReS 2 ,[28] PtS 2 /WSe 2 ,[29] and Te/WS 2 [30].…”

Room‐Temperature Sodium–Sulfur Batteries: Rules for Catalyst Selection and Electrode Design

“…In RT Na-S systems, the unoccupied p orbits of NaPS species and d orbits of transition-metal species are considered as active sites. [34][35][36][37] And the electronic concentration of NaPS in Fermi energy is affected by the distance of d band center or p band center toward Fermi levels. Reducing the energy gap between the p band center of NaPS and d band center of transition-metal ions can significantly enhance the electronic concentrations of NaPS in Fermi level, thus resulting in rapid interfacial electronic kinetics and improved performance of RT Na-S batteries.…”