Two-dimensional (2D) semiconductors are very promising channel materials in next-generation field effect transistors (FETs) due to the enhanced gate electrostatics and smooth surface. Two new 2D materials, arsenene and antimonene (As and Sb analogues of graphene), have been fabricated very recently. Here, we provide the first investigation of the many-body effect, carrier mobility, and device performance of monolayer (ML) hexagonal arsenene and antimonene based on accurate ab initio methods. The quasi-particle band gaps of ML arsenene and antimonene by using the GW approximation are 2.47 and 2.38 eV, respectively. The optical band gaps of ML arsenene and antimonene from the GW-Bethe–Salpeter equation are 1.6 and 1.5 eV, with exciton binding energies of 0.9 and 0.8 eV, respectively. The carrier mobility is found to be considerably low in ML arsenene (21/66 cm2/V·s for electron/hole) and moderate in ML antimonene (150/510 cm2/V·s for electron/hole). In terms of the ab initio quantum transport simulations, the optimized sub-10 nm arsenene and antimonene FETs can satisfy both the low power and high performance requirements in the International Technology Roadmap for Semiconductors in the next decade. Together with the observed high stability under ambient condition, ML arsenene and antimonene are very attractive for nanoscale optoelectronic and electronic devices.

Graphdiyne (GDY), a newly emerging 2D carbon allotrope, has been widely explored in various fields owing to its outstanding electronic properties such as the intrinsic bandgap and high carrier mobility. Herein, GDY‐based photoelectrochemical‐type photodetection is realized by spin‐coating ultrathin GDY nanosheets onto flexible poly(ethylene terephthalate) (PET) substrates. The GDY‐based photodetectors (PDs) demonstrate excellent photo‐responsive behaviors with high photocurrent (Pph, 5.98 µA cm‐2), photoresponsivity (Rph, 1086.96 µA W‐1), detectivity (7.31 × 1010 Jones), and excellent long‐term stability (more than 1 month). More importantly, the PDs maintain an excellent Pph after 1000 cycles of bending (4.45 µA cm‐2) and twisting (3.85 µA cm‐2), thanks to the great flexibility of the GDY structure that is compatible with the flexible PET substrate. Density functional theory (DFT) calculations are adopted to explore the electronic characteristics of GDY, which provides evidence for the performance enhancement of GDY in alkaline electrolyte. In this way, the GDY‐based flexible PDs can enrich the fundamental study of GDY and pave the way for the exploration of GDY heterojunction‐based photodetection.

Two-dimensional molecular crystals, consisting of zero-dimensional molecules, are very appealing due to their novel physical properties. However, they are mostly limited to organic molecules. The synthesis of inorganic version of two-dimensional molecular crystals is still a challenge due to the difficulties in controlling the crystal phase and growth plane. Here, we design a passivator-assisted vapor deposition method for the growth of two-dimensional Sb2O3 inorganic molecular crystals as thin as monolayer. The passivator can prevent the heterophase nucleation and suppress the growth of low-energy planes, and enable the molecule-by-molecule lateral growth along high-energy planes. Using Raman spectroscopy and in situ transmission electron microscopy, we show that the insulating α-phase of Sb2O3 flakes can be transformed into semiconducting β-phase under heat and electron-beam irradiation. Our findings can be extended to the controlled growth of other two-dimensional inorganic molecular crystals and open up opportunities for potential molecular electronic devices.

Non-layered tellurium (Te) is a promising material for applications in transistor and optoelectronic devices for its advantages in excellent intrinsic electronic and optoelectronic properties. However, the poor photodetection performance and relatively uncertain stability of tellurene under ambient conditions greatly limit the practical applications. In order to improve the performance of tellurene-based materials, Te@Se roll-to-roll nanotubes with different selenium (Se) contents synthesized by epitaxial growth of Se on Te nanotubes are, for the first time, employed to fabricate working electrodes for photoelectrochemical (PEC)-type broadband photodetection. They exhibit not only a preferably enhanced capacity for self-powered broadband photodetection but also significantly improved photocurrent density and stability in various aqueous environments (HCl, NaCl, and KOH solutions), compared to tellurene-based photodetectors. It is anticipated that the present work can open up new possibilities for high-performance tellurene-based optoelectronic devices.

Nanocrystals (NCs) with identical components and sizes but different crystal structures could not be distinguished by conventional absorption and emission spectra. Herein, we find that circular dichroism (CD) spectroscopy can easily distinguish the CdSe nanoplatelets (NPLs) with different crystal structures of wurtzite (WZ) and zincblende (ZB) with the help of chiral L-or D-cysteine ligands. In particular, the CD signs of the first excitonic transitions in WZ and ZB NPLs capped by the same chiral cysteine are opposite. Theoretic calculation supports the viewpoint of different crystal structures and surfaces arrangements between WZ and ZB NPLs contributing to this significant phenomenon. The CD peaks appearing at the first excitonic transition band of WZ or ZB CdSe NPLs are clearly assigned to the different transition polarizations along 4p (x,y,z),Se → 5s Cd or 4p (x,y),Se → 5s Cd. This work not only provides a deep insight into the origin of the optical activity inside chiral semiconductor nanomaterials but also proposes the design principle of chiral semiconductor nanocrystals with high optic activity.