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The external quantum efficiency of state-of-the-art quantum dot light-emitting diodes is limited by the low photon out-coupling efficiency. Light-emitting diodes using oriented nanostructures such as nanorods, nanoplatelets and dot-in-disc nanocrystals favour photon out-coupling; however, their internal quantum efficiency is often compromised and thus achieving a net gain has proved challenging. Here we report isotropic-shaped quantum dots featuring a mixed-crystallographic structure composed of wurtzite and zinc blende phases. The wurtzite phase promotes dipole–dipole interactions that orient quantum dots in solution-processed films, whereas the zinc blende phase helps lift the electronic state degeneracy to enable directional light emission. These combined features improve photon out-coupling without compromising internal quantum efficiency. Fabricated light-emitting diodes exhibit an external quantum efficiency of 35.6% and can be continuously operated with an initial brightness of 1,000 cd m – 2 for 4.5 years with a minimal performance loss of about 5%. Dipole–dipole interactions in mixed-phase CdZnSeS quantum dots enable the effective orientation of the quantum dots and improved photon out-coupling when employed in a light emitting diode.

Ferroelectric materials, the charge equivalent of magnets, have been the subject of continued research interest since their discovery more than 100 years ago. The spontaneous electric polarization in these crystals, which is non-volatile and programmable, is appealing for a range of information technologies. However, while magnets have found their way into various types of modern information technology hardware, applications of ferroelectric materials that use their ferroelectric properties are still limited. Recent advances in ferroelectric materials with wurtzite and fluorite structure have renewed enthusiasm and offered new opportunities for their deployment in commercial-scale devices in microelectronics hardware. This Review focuses on the most recent and emerging wurtzite-structured ferroelectric materials and emphasizes their applications in memory and storage-based microelectronic hardware. Relevant comparisons with existing fluorite-structured ferroelectric materials are made and a detailed outlook on ferroelectric materials and devices applications is provided. This Review presents the most recent ferroelectric materials with wurtzite structure and emphasizes applications in memory and storage-based microelectronic hardware.

Interface engineering by local polarization using piezoelectric1–4, pyroelectric5,6 and ferroelectric7–9 effects has attracted considerable attention as a promising approach for tunable electronics/optoelectronics, human–machine interfacing and artificial intelligence. However, this approach has mainly been applied to non-centrosymmetric semiconductors, such as wurtzite-structured ZnO and GaN, limiting its practical applications. Here we demonstrate an electronic regulation mechanism, the flexoelectronics, which is applicable to any semiconductor type, expanding flexoelectricity10–13 to conventional semiconductors such as Si, Ge and GaAs. The inner-crystal polarization potential generated by the flexoelectric field serving as a ‘gate’ can be used to modulate the metal–semiconductor interface Schottky barrier and further tune charge-carrier transport. We observe a giant flexoelectronic effect in bulk centrosymmetric semiconductors of Si, TiO2 and Nb–SrTiO3 with high strain sensitivity (>2,650), largely outperforming state-of-the-art Si-nanowire strain sensors and even piezoresistive, piezoelectric and ferroelectric nanodevices14. The effect can be used to mechanically switch the electronics in the nanoscale with fast response (<4 ms) and high resolution (~0.78 nm). This opens up the possibility of realizing strain-modulated electronics in centrosymmetric semiconductors, paving the way for local polarization field-controlled electronics and high-performance electromechanical applications.Tuning a flexoelectric polarization field in centrosymmetric semiconductor single crystals enables the observation of a giant flexoelectronic effect.

The rapid recombination of photoinduced charge carriers in semiconductors fundamentally limits their application in photocatalysis. Herein, we report that a superlattice interface and S-scheme heterojunction based on Mn 0.5 Cd 0.5 S nanorods can significantly promote ultrafast charge separation and transfer. Specifically, the axially distributed zinc blende/wurtzite superlattice interfaces in Mn 0.5 Cd 0.5 S nanorods can redistribute photoinduced charge carriers more effectively when boosted by homogeneous internal electric fields and promotes bulk separation. Accordingly, S-scheme heterojunctions between the Mn 0.5 Cd 0.5 S nanorods and MnWO 4 nanoparticles can further accelerate the surface separation of charge carriers via a heterogeneous internal electric field. Subsequent capture of the photoelectrons by adsorbed H 2 O is as fast as several picoseconds which results in a photocatalytic H 2 evolution rate of 54.4 mmol·g −1 ·h −1 without any cocatalyst under simulated solar irradiation. The yields are increased by a factor of ~5 times relative to control samples and an apparent quantum efficiency of 63.1% at 420 nm is measured. This work provides a protocol for designing synergistic interface structure for efficient photocatalysis. Limited charge separation is a major challenge in creating efficient semiconductor photocatalysis. This work introduces a superlattice interface and S-scheme heterojunction for ultrafast charge separation and transfer in photocatalytic H 2 evolution.

The influence of hydrostatic pressure on the polaron energy level in wurtzite GaN/AlxGa1-xN quantum well is studied by a Lee-Low-Pines variational method, and the numerical results of the ground state energy, transition energy and contributions of different phonons to polaron energy (polaron effects) are given as functions of pressure p and composition x. The results show that the ground state energy and transition energy in the wurtzite GaN/AlxGa1-xN quantum well decrease with the increase of the hydrostatic pressure p, and increase with the increase of the composition x. The contributions of different phonons to polaron energy with pressure p and composition x are obviously different. With the increase of hydrostatic pressure, the contribution of half-space phonon, confined phonon and the total contribution of phonons of all branches increases obviously, while the contribution of interface phonon slowly increases. During the increase of the composition, the contribution of interface phonon decreases and the contribution of half-space phonon increases slowly, while the contribution of confined phonon and the total contribution of phonons increases significantly. In general, the electron-optical phonon interaction play an important role in electronic states of GaN/AlxGa1-xN quantum wells and can not be neglected.

In this work, Chromium (Cr) doped Zinc Oxide (ZnO) nano-structured thin films were deposited using ultrasonic spray pyrolysis technique on glass substrate at different concentration (0,1,3,5,10 wt%) with a substrate temperature of 350 o C. The effect of chromium on zinc oxide thin films was studied to extract the structural, optical and electrical characteristics using XRD, UV-Vis spectroscopy and Hall effect measurement instruments respectively. The work on undoped ZnO showed hexagonal wurtzite structure, with an ideal orientation of (101). The increase in strain with respect to doping concentration confirmed decrease in the crystallite size. Variation in the surface roughness on doping Cr is observed. The optical results depicted influence of Cr doping resulted in the decrease in transmittance. Band-gap (BG) obtained using Tauc’s plot was seen to vary with Cr-doping. Hall effect measurement at standard conditions observed decreases in carrier concentration, and indicating the conduction to be n-type. The study of third-order nonlinear optical characteristics, such as susceptibility χ (3) , nonlinear refractive index (NRI) (𝑛 2 ), and nonlinear absorption coefficient (β) was carried out. These findings suggest that the films consist of self-defocusing nonlinearity. The overall results confirmed that the structural and optical results were dependent on Cr concentration in ZnO.

Green synthesis of nanoparticles by biological systems especially plant extracts has become an emerging field in nanotechnology. In this study, zinc oxide nanoparticles were synthesized using Laurus nobilis L. leaves aqueous extract and two different zinc salts (zinc acetate and zinc nitrate) as precursors. The synthesized nanoparticles were characterized by Ultraviolet-Visible spectroscopy (UV-Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction analysis (XRD), Energy-Dispersive X-ray analysis (EDX) and Scanning Electron Microscopy (SEM). UV-Vis spectra showed typical absorption peaks in around 350 nm due to their large excitation binding energy at room temperature. Chemical bond formations of zinc oxide were confirmed by FT-IR analyses. XRD results revealed the formation of hexagonal wurtzite structure, and SEM analyses showed spherical shape with the average size (21.49, 25.26) nm for the synthesized nanoparticles by zinc acetate and zinc nitrate respectively. EDX analyses confirmed high purity for the synthesized nanoparticles.

The adhesion of deleterious bacteria on titanium substrates not only causes economic losses but also endangers human life and health. The study is expected to address the challenging issues of using ZnO as an antibacterial material, including low bactericidal efficiency without lighting, susceptibility to ZnO cluster formation, and easy adhesion of bacteria to its surface. It is proposed that the prepared ZnO nanorod arrays with a hexagonal wurtzite structure on the surface of titanium-based materials can address the issue of ZnO cluster formation. Remarkably, a mere 3.49 g cm−2 of decorated Ag/AgCl achieves over 99% sterilization efficiency without lighting. The incorporation of FAS (1H,1H,2H,2H-perfluorodecyltrimethoxysilane) molecules with low surface energy enables the prepared Ti@ZnO@Ag/AgCl@FAS to attain a Cassie–Baxter wetting state, thereby imparting exceptional bacterial anti-adhesion properties exceeding 99.50%. Furthermore, antibacterial and anti-adhesion models have been proposed to elucidate the underlying mechanisms. This innovative approach is anticipated to be adaptable for application across various material substrates, which opens up a new avenue for the application of the antibacterial and bacterial anti-adhesion properties on the surface of ZnO materials.

The atomic configuration and relaxation behavior of wurtzite aluminum nitride (AlN) low-index surfaces play a decisive role in their interfacial properties. In this work, we systematically investigated six possible termination structures (A-F types) of the (001), (100), and (110) surfaces using first-principles calculations. By comparing the total energies under the Local Density Approximation (LDA) and Generalized Gradient Approximation (GGA), we found that the (001)-A type structure (Al-terminated surface) exhibits the lowest energy (LDA: -2649.96 eV, GGA: -2639.50 eV), confirming its thermodynamic stability. Surface energy calculations revealed convergence to 3.05–3.16 J/m2 when the atomic layers ≥ 12 and vacuum thickness ≥ 1 nm. This study provides atomic-scale theoretical insights for AlN surface engineering.