The performance of red InP and blue ZnTeSe-based quantum dots (QDs) and corresponding QD light emitting diodes (QLEDs) has already been improved significantly, whose external quantum efficiencies (EQEs) and luminances have exceeded 20% and 80,000 cd m-2, respectively. However, the inferior performance of the green InP-based device hinders the commercialization of full-color Cd-free QLED technology. The ease of oxidation of the highly reactive InP cores leads to high non-radiative recombination and poor photoluminescence quantum yield (PL QY) of the InP-based core/shell quantum dots (QDs), limiting the performance of the relevant QLEDs. Here, we proposed a fluoride-free synthesis strategy to in-situ passivate the InP cores, in which zinc myristate reacted with phosphine dangling bonds to form Zn-P protective layer and protect InP cores from the water and oxygen in the environment. The resultant InP/ZnSe/ZnS core/shell QDs demonstrated a high PL QY of 91%. The corresponding green-emitting electroluminescence devices exhibited a maximum EQE of 12.74%, along with a luminance of over 175,000 cd m^-2 and a long T₅₀@100 cd m^-2 lifetime of over 20,000 h.

Zero-dimensional graphene quantum dots (GQDs) exhibit many different properties, such as strong fluorescence, nonzero bandgap and solubility in solvents, compared to two-dimensional graphene. GQDs are biocompatible and have low toxicity; hence, they are widely used in the biomedical field. The edge effect of GQDs is of particular interest because edge modification can regulate the performance of nanomaterials. In this review, various preparation methods for GQDs, which can be divided into three main categories, namely top-down, bottom-up and chemical methods, are discussed. The unique optical, electrical, thermal and magnetic properties of GQDs are reviewed. The functionalization of GQDs by doping with heteroatoms and forming composites with other materials is studied, and the characteristics of these GQDs are also discussed. The applications of these GQDs in the fields of optics, electricity, optoelectronics, biomedicine, energy, agriculture and other emerging interdisciplinary fields are reviewed to highlight the enormous potential of nanomaterials. This review reports on the recent advancement in GQD research and suggests future directions for the development of GQDs.

A 2D heterostructure with proximity coupling of magnetism and topology can provide enthralling prospects for hosting new quantum states and exotic properties that are relevant to next-generation spintronic devices. Here, we synthesize a delicate van der Waals (vdW) heterostructure of CrTe2/Bi2Te3 at the atomic scale via molecular beam epitaxy. Low-temperature scanning tunneling microscopy/spectroscopy measurements are utilized to characterize the geometric and electronic properties of the CrTe₂/Bi₂Te₃ heterostructure with a compressed vdW gap. Detailed structural analysis reveals complex interfacial structures with diversiform step heights and intriguing moiré patterns. The formation of the interface is ascribed to the embedded characteristics of CrTe₂ and Bi₂Te₃ by sharing Te atomic layer upon interfacing, showing intercoupled features of electronic structure for CrTe₂ and Bi₂Te₃. Our study demonstrates a possible approach to construct artificial heterostructures with different types of ordered states, which may be of use for achieving tunable interfacial Dzyaloshinsky–Moriya interactions and tailoring the functional building blocks in low dimensions.

Quasi-two-dimensional (quasi-2D) perovskites are promising materials for potential application in light-emitting diodes (LEDs) due to their high exciton binding energy and efficient emission. However, their luminescent performance is limited by the low-n phases that act as quenching luminescence centers. Here, a novel strategy for eliminating low-n phases is proposed based on the doping of strontium bromide (SrBr₂) in perovskites, in which SrBr₂ is able to manipulate the growth of quasi-2D perovskites during their formation. It was reasonably inferred that SrBr₂ readily dissociated strontium ions (Sr²⁺) in dimethyl sulfoxide solvent, and Sr²⁺ was preferentially adsorbed around [PbBr6]⁴⁻ through strong electrostatic interaction between them, leading to a controllable growth of quasi-2D perovskites by appropriately increasing the formation energy of perovskites. It has been experimentally proved that the growth can almost completely eliminate low-n phases of quasi-2D perovskite films, which exhibited remarkably enhanced photoluminescence. A high electroluminescent efficiency matrix green quasi-2D perovskite-LED (PeLED) with a pixel density of 120 pixels per inch fabricated by inkjet printing technique was achieved, exhibiting a peak external quantum efficiency of 13.9%, which is the most efficient matrix green quasi-2D PeLED so far to our knowledge.

Chalcogenide phase-change materials (PCMs), in particular, the flagship Ge2Sb2Te5 (GST), are leading candidates for advanced memory applications. Yet, GST in conventional devices suffer from high power consumption, because the RESET operation requires melting of the crystalline GST phase. Recently, we have developed a conductive-bridge scheme for low-power phase-change application utilizing a self-decomposed Ge-Sb-O (GSO) alloy. In this work, we present thorough structural and electrical characterizations of GSO thin films by tailoring the concentration of oxygen in the phase-separating GSO system. We elucidate a two-step process in the as-deposited amorphous film upon the introduction of oxygen: with increasing oxygen doping level, germanium oxides form first, followed by antimony oxides. To enable the conductive-bridge switching mode for femtojoule-level RESET energy, the oxygen content should be sufficiently low to keep the antimony-rich domains easily crystallized under external electrical stimulus. Our work serves as a useful example to exploit alloy decomposition that develops heterogeneous PCMs, minimizing the active switching volume for low-power electronics.

Scanning probe microscopy (SPM) allows the spatial imaging, measurement, and manipulation of nano and atomic scale surfaces in real space. In the last two decades, numerous advanced and functional SPM methods, particularly atomic force microscopy (AFM), have been developed and applied in various research fields, from mapping sample morphology to measuring physical properties. Herein, we review the recent progress in functional AFM methods and their applications in studies of two-dimensional (2D) materials, particularly their interfacial physical properties on the substrates. This review can inspire more exciting application works using advanced AFM modes in the 2D and functional materials fields.