Browse Articles

Optoelectronic performance enhancement of 1–5  <i>μ</i> m InGaN-based micro-LEDs using chemical etching coupled with dielectric passivation

Although InGaN-based micro-light-emitting diodes (micro-LEDs) have been extensively studied as key components for next-generation display technologies, the performance of micro-LEDs smaller than 5 μm remains severely constrained by the sidewall effect, posing an urgent challenge to be addressed. This study successfully fabricated InGaN-based micro-LEDs with dimensions ranging from 1 to 5 μm by introducing a coupled chemical etching with dielectric passivation technique. It is revealed that the peak external quantum efficiency (EQE) of all devices significantly improved after coupled chemical etching, while their surface recombination velocity decreased significantly. Moreover, this enhancement in peak EQE becomes more pronounced as the device size decreases from 5 to 1 μm. APSYS simulations further indicate that as the sidewall defect density decreases, the distribution of holes across different quantum wells becomes more uniform, and the radiative recombination rate relative to the Shockley–Read–Hall rate significantly increases, which is in excellent agreement with the experimental results. More importantly, the peak EQE of 1 and 5 μm micro-LEDs reached 14.01% and 40.46%, respectively, increasing by 363% and 151% compared to that without coupled chemical etching. These findings validate the effectiveness of chemical etching coupled with dielectric passivation technology in micro-LED manufacturing, and also reveal the significant impact of sidewall defects in size-dependent efficiency.

Gate tunable photodetection and imaging in WS2 phototransistors enabled by a lithium niobate functional substrate

Heterogeneous integration with two-dimensional materials offers a promising route to address the photoelectric conversion challenges of lithium niobate (LiNbO3, LN). However, previous works have mostly relied on the weak spontaneous polarization of LN, which underutilizes the potential of ferroelectric polarization and lacks sufficient degrees of freedom for programmable control. In this work, we fabricate a LiNbO3/WS2 phototransistor via photolithography and van der Waals transfer, and back-gate voltage is employed to achieve programmable modulation of the photocurrent magnitude and polarity, which can be interpreted through a parallel-plate capacitor model combined with the pyroelectric effect. Moreover, the thin-film LN enables back-gate modulation while retaining the ferroelectric and pyroelectric functionalities of LN, allowing the photoresponse of the WS2 channel to be continuously regulated by the gate voltage, leading to exceptional programmable performance with Ilight/Idark ratio tunable from 26.6 to 66 437.82 and responsivity from 5.47 to 492.35 A/W, while photocurrent imaging further reveals that the back-gate bias continuously adjusts the trade-off between image brightness and contrast. This work establishes that functional polarized substrates can provide a new system-level control dimension for two-dimensional optoelectronic devices, paving the way for programmable detection, adaptive imaging, and task-oriented intelligent sensing.

5–24 GHz high <i>f-Q</i> product multi-mode surface acoustic wave resonances in LiNbO3/SiC heterostructures

This work reports multi-mode surface acoustic wave resonances in a lithium niobate on silicon carbide (LiNbO3/SiC) heterostructure, achieving high resonant frequency-quality factor (f-Q) products over a broad frequency range from 5 to 24 GHz. By employing a 600-nm-thick LiNbO3 functional layer, multiple high-velocity acoustic modes with wavelengths (λ) ranging from 0.24 to 0.8 μm are effectively confined. This strong energy confinement arises from the large acoustic impedance mismatch between the LiNbO3 thin film and the high-phase-velocity SiC substrate, enabling the selected modes to consistently exhibit high f-Q products exceeding 1012 with a maximum f-Q product of 1.6 ×1013 achieved for the SH1 mode at 10.6 GHz. The operating frequency is further extended to the millimeter-wave regime at 24.45 GHz with a shorter λ of 0.24 μm while maintaining an excellent f-Q product of 6 ×1012. These results highlight the strong potential of the LiNbO3/SiC platform for the development of frequency-scalable, high-performance acoustic devices for next-generation communication systems.

Molecular beam epitaxy and characterization of wurtzite LaAlN

We report the molecular beam epitaxy and structural characterization of single-phase wurtzite LaxAl1−xN thin films, with a La composition as high as x=0.20. In situ reflection high-energy electron diffraction confirms epitaxial film formation, and atomic force microscopy reveals sub-nanometer surface roughness for all compositions investigated. High-resolution x-ray diffraction and scanning transmission electron microscopy further confirm c-axis orientation, high crystalline quality, and precise in-plane epitaxial alignment. Importantly, atomic-resolution structural analysis demonstrates a continuous decrease in the c/a lattice-parameter ratio with increasing La content. In addition, out-of-plane piezoresponse force microscopy measurements show an enhanced effective d33, increasing from 5.00 pm/V for AlN to 7.66 pm/V for La0.20Al0.80N. These results establish LaAlN as a promising new wurtzite nitride alloy platform for future wide bandgap electronics, optoelectronics, and quantum photonics.

Ablation removal of transport-blocking defects in surface-electrode ion traps

We demonstrate in situ removal of a transport-blocking defect on a surface-electrode ion trap device using a Q-switched Nd:YAG 532 nm pulsed ablation laser. This approach eliminates the need to vent and rebake the vacuum system, providing a low-overhead defect-remediation technique well suited for ion-shuttling architectures where system modifications typically incur substantial downtime—particularly in shuttling focused experiments operating at temperatures that necessitate bakes. Additionally, the hardware used is readily available in many ion trap laboratories, making this solution attractive to experiments operating in such regimes. Following ablation, we observe near-unit shuttling success rates across the previously obstructed region and measure micromotion levels that remain within acceptable limits. This technique enables rapid, reliable restoration of transport pathways without interruption to experimental operation.

Huasong Ai

3D‐Printable Nanoporous Thermosets via Disulfide‐Based Polymerization‐Induced Microphase Separation

ABSTRACT Interconnected nanoporous polymer networks are central to applications that demand rapid mass transport, yet their fabrication by polymerization‐induced microphase separation (PIMS) remains constrained by fixed macroCTA polarity, limited formulation compatibility, and difficult translation to additive manufacturing. Here, we address these limitations by introducing a PIMS strategy utilizing chemically degradable macroCTAs with systematically tunable hydrophilicity. These macroCTAs were synthesized via reversible addition−fragmentation chain‐transfer copolymerization of α‐lipoic acid or ethyl lipoate with various acrylates. This diverse library of macroCTAs enabled the preparation of microphase‐separated materials across a broad range of monomer and crosslinker chemistries, which were readily converted into nanoporous thermosets with well‐defined pore sizes (24–42 nm) via selective disulfide cleavage. Critically, these photocurable resins are compatible with liquid‐crystal display 3D printing, allowing the fabrication of complex, hierarchical architectures that can be directly etched to generate embedded nanoscale porosity while preserving structural integrity. Collectively, tunable and degradable macroCTAs bridge 3D‐printable form factors with programmable nanoscale structure, providing a general route to hierarchically structured materials for separations, catalysis, and advanced manufacturing.

Sustainable Synthesis of Ammonium Nitrate From Air and Water via Tandem Plasma‐Electrolyzer System

ABSTRACT Ammonium nitrate (NH 4 NO 3 ) is an indispensable high‐nitrogen fertilizer, yet its conventional industrial production via the energy‐intensive Haber–Bosch and Ostwald processes accounts for a significant global carbon footprint. Herein, we report an alternative method for directly synthesizing NH 4 NO 3 from air and water by integrating plasma‐assisted nitrogen oxidation (pNOR) with paired electrocatalytic nitrite reduction and oxidation (eNO 2 – RR/eNO 2 – OR) in a neutral medium (0.5 M phosphate buffer solution). Key to this technology is the rational design of a Co 3wt% Cu@C cathode catalyst for the critical eNO 2 – RR step, which operates via a dual‐active‐site mechanism: Cu sites adsorb and activate NO 2 – , while adjacent Co sites efficiently dissociate water to generate reactive hydrogen species (*H). Subsequent hydrogen spillover from Co to Cu sites dramatically accelerates NO 2 – hydrogenation to NH 4 + , achieving almost 100% Faradaic efficiency toward NH 3 and a high NH 4 + yield rate of 512 µmol cm −2  h −1 at a low potential of –0.5 V vs. RHE. The integrated pNOR‐eNO 2 – RR/eNO 2 – OR system operates stably over 210 h (affording 8.5 mmol h −1 NH 4 NO 3 ) with significant techno‐economic advantages. Further, the obtained NH 4 NO 3 solutions can serve as N‐P‐K fertilizer for plant growth, offering a route to on‐demand, on‐site fertilizer synthesis from air and water for smart agriculture.

Substrate‐Controlled Dearomative Cycloadditions of Perfluoronaphthalenes via Visible‐Light Energy Transfer Catalysis: Switchable Access to [2+2], [4+2], and Diastereoconvergent Cycloadducts

ABSTRACT We report the first substrate‐controlled intermolecular dearomative cycloaddition of polyfluoronapthalenes in which the substitution pattern of the olefin coupling partner governs the mode of cycloaddition. Under visible‐light energy transfer ( VL EnT) catalysis, monosubstituted olefins react with octafluoronaphthalene to give dual dearomative ortho [2+2] cycloadducts selectively. In comparison, 1,1‐disubstituted olefins afford the corresponding para [4+2] cycloadducts with complete regiospecificity under otherwise identical conditions. Trisubstituted olefins engage in a diastereoconvergent [4+2] cycloaddition, delivering a single diastereomeric product regardless of the olefin geometry. This mild, operationally simple strategy provides direct access to structurally diverse, perfluorinated three‐dimensional molecular scaffolds, frameworks of increasing importance in drug discovery and materials science, from readily available starting materials in a single synthetic step. Control experiments and density functional theory calculations elucidated the VL EnT catalysis and olefin‐substitution‐controlled switching between distinct dearomative cycloaddition modes.

Correction to “Sono‐Triggered Cascade Lactate Depletion by Semiconducting Polymer Nanoreactors for Cuproptosis‐Immunotherapy of Pancreatic Cancer”

Synergistic Dual <i>d</i> ‐Band Engineering at the Ru‐N ₄ /MXene Interface for High‐Efficiency and Long‐Lived Li–CO ₂ Batteries

ABSTRACT The cyclability of Li–CO 2 batteries is fundamentally limited by the sluggish kinetics of Li 2 CO 3 formation and decomposition. In this work, we develop a Ru‑N 4 single‑atom catalyst anchored on MXene (MX‑Ru SA ), in which the atomic interface establishes a synergistic dual d ‑band center to overcome this kinetic constraint. The N coordination modifies the electronic state of Ru, upshifting its d ‐band center to strengthen intermediate adsorption and steer the growth of vertically aligned Li 2 CO 3 nanosheets that facilitate efficient electron and ion transport. Meanwhile, the presence of Ru‐N 4 sites modulates the electronic structure of the MXene support, optimizing the d ‐band center of Ti, which weakens the Li─O bonds in Li 2 CO 3 and significantly reduces its decomposition barrier. As a result, the Li–CO 2 battery with MX‑Ru SA delivers a high discharge capacity of 14757 mA h g −1 , along with an ultralow charging overpotential of 0.56 V and a long cycle life over 3000 h at 100 mA g −1 . This work demonstrates interfacial dual d ‑band synergy as a promising design principle toward high‑performance catalysts for metal‐gas battery systems.

Pd Single‐Atom‐Doped Cu ₃ Co Quantum Dots With Optimized Hydrogenation Kinetics for Versatile Aluminum‐Nitrate Primary Battery With Synchronous Energy Harvesting and Waste Valorization

ABSTRACT The rational design of nitrate batteries enabling simultaneous electricity generation and pollutant degradation is highly promising, yet most reported systems, such as Zn‐nitrate or aldehyde‐nitrate batteries, face critical limitations, including sluggish cathodic nitrate reduction kinetics, high anode material cost, low‐value anode reaction products, inferior open‐circuit potential (OCP), and limited power output. Optimizing catalyst activity and NH 3 selectivity via structure‐activity relationships is pivotal to enhancing the electrical output efficiency of such batteries. Herein, we report a Pd single‐atom‐doped Cu 3 Co quantum dots electrocatalyst (Pd sa ‐Cu 3 Co QDs), which modulates H* adsorption to accelerate the key hydrogenation steps of NO 3 RR, achieving a positive onset of +0.18 V (vs. RHE) and nearly 100% Faradaic efficiency (FE) for NH 3 at −0.5 V (vs. RHE). A novel Al‐NO 3 − primary battery is further constructed by coupling cathodic NO 3 RR with anodic aluminum oxidation, enabling cathodic NH 3 production and anodic conversion of waste aluminum (e.g., used Cola cans) to green H 2 and high‐value alums. This battery exhibits an OCP of 1.26 V, 8.85 mW cm −2 peak power density, and an FE of 48.78% NH 3 , 56.88% H 2 , and yield 56.10% alum, significantly enhancing its economic viability and practical application.

Outside Front Cover: 3D‐Printable Nanoporous Thermosets Via Disulfide‐Based Polymerization‐Induced Microphase Separation (Angew. Chem. Int. Ed. 33/2026)

Copper (II) Chloride Mediated Interfacial Permeation for High‐Efficient and Stable Wide‐Bandgap Perovskite Solar Cells

ABSTRACT Wide‐bandgap (WBG) perovskite solar cells (PSCs) are crucial for high‐efficiency tandem photovoltaics. However, their performance is severely limited by lattice disorder at the buried interface, which leads to the accumulation of deep‐level defects and interfacial morphological inhomogeneities, thereby inducing pronounced non‐radiative recombination and halide segregation. Here, we report a copper (II) chloride (CuCl 2 ) mediated interfacial permeation strategy that achieves the redox mediation and halide coordination, thereby stabilizing the interfacial chemical state, suppressing the formation of deep‐level defects. The strategy effectively suppresses lattice disorder at the buried interface, while simultaneously constructing an efficient hole‐transfer structure, thus enhancing interfacial phase stability and charge‐transport properties. Consequently, our modified 1.79 eV WBG PSCs exhibit minimized non‐radiative recombination losses and superior charge transport, achieving state‐of‐the‐art performance with an open circuit voltage ( V OC ) of 1.35 V, a fill factor of 84.29%, and power conversion efficiency (PCE) of 21.24%, one of the highest reported so far. The device can maintain 91% of its original efficiency after 1400 h of maximum power point tracking.

A General Platform for <i>S</i> ‐Stereogenic α‐Fluoroalkyl S(IV/VI) Compounds via Enantioselective Radical Fluoroalkylation of Sulfenamides

ABSTRACT α‐Fluoroalkyl‐substituted high‐valent sulfur motifs are important structural elements in fluorinated molecule design and exhibit broad application potential in diverse fields. However, access to S ‐stereogenic α‐fluoroalkyl S(IV/VI) compounds still relies largely on classical resolution, resulting in limited efficiency and selectivity. We herein report a copper‐catalyzed asymmetric radical C–S cross‐coupling that effectively tames highly reactive α‐fluoroalkyl radicals, enabled by a sequential stereodiscrimination–chirality transfer strategy, providing rapid access to S ‐chiral α‐fluoroalkyl sulfilimines. Integrated with downstream transformations, this reaction serves as a general and systematic platform for S ‐chiral α‐fluoroalkyl S(IV/VI) compounds. The synthetic utility of the method is demonstrated by gram‐scale synthesis and concise access to diverse chiral fluoroalkyl reagents and bioisosteres of sulfur‐containing drugs.

Antiaromaticity‐Driven Enhancement of Single‐Molecule Electrical Conductance by <i>s</i> ‐Indacene Molecular Bridges

ABSTRACT High electrical conductance of antiaromatic molecules compared with aromatic counterparts at the single‐molecule level has been a topic of controversy, with only a few previous experimental proofs. We synthesized length‐matched molecular wires incorporating 12 π‐electron antiaromatic s ‐indacene (Ind) and 14 π‐electron aromatic benzodithiophene (BDT) cores with different anchoring modes and measured the single‐molecule electrical conductance (SMEC) by scanning tunneling microscopy‐break junction method, validating that antiaromatic cores significantly enhance the conductance. For the diagonally anchored systems, the antiaromatic Ind derivative exhibits SMEC approximately 10 times higher than that of its aromatic BDT analogue, thanks to the cooperative effects of a linear conjugation pathway and the narrow gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) that brings favorable frontier molecular orbital (FMO) alignment with the electrode Fermi level. Notably, for the horizontally anchored systems, the Ind derivative exhibits SMEC 2.8 times higher than that of its BDT counterpart, as its antiaromaticity‐driven FMO alignment overtakes the cross‐conjugation pathway. Additionally, introduction of electron‐withdrawing trifluoromethyl groups to the Ind core shifts the LUMO closer to the Fermi level, resulting in 1.5 times higher conductance. These results definitively demonstrate the enhancement of SMEC driven by antiaromaticity.

Excited‐State Antiaromaticity in Nonbenzenoid Aromatics: Examining the Dynamics of Intramolecular Proton Transfer With a Small Driving Force

ABSTRACT The relief of excited‐state antiaromaticity (ESAA) is a powerful driving force that underpins the photochemical behavior of photoexcited aromatic molecules. Photo‐induced isomerization, cycloaddition, or proton transfer pathways alleviate the large energetic destabilization caused by ESAA. However, the excited‐state dynamics of annulenes displaying only weak ESAA remain largely unexplored. Here, we fine‐tune the electronic character of a series of annulenes to minimize their ESAA. Excited‐state proton transfer (ESPT) converts hydroxytropyliums (HTs) and hydroxybenzotropyliums (HBTs) to their nonaromatic tautomers, which are only slightly lower in energy than the excited‐state antiaromatic forms. As a result of this near‐degeneracy, we find that HBTs exhibit weak photoacidity (pKa drop of 0.3–1.2 units) and unusually slow, reversible ESPT, proceeding on the ns timescale rather than the typical ps timescale. The fluorescence spectra of these HBTs display the hallmarks of ESPT emitters: (i) dual fluorescence; (ii) excitation‐dependent emission; and (iii) large Stokes shifts. The driving force for this ESPT is increased by the addition of electron‐donating groups, which promote intramolecular charge transfer. Our results demonstrate that judicious structural changes can moderate the ESAA of nonbenzenoid annulenes, minimizing the driving force for ESPT, which leads to slow proton transfer kinetics and weak photoacidity.

Catalyst‐Free Upcycling of Polyethylene Waste Into Oxidized Polyethylene Wax

ABSTRACT Polyethylene (PE) accounts for 36% of the total plastic waste by mass. However, its inherent chemical stability poses significant challenges for chemical recycling, including energy‐intensive processing, costly catalysts, and thermodynamic constraints that result in low‐value hydrocarbon products. Herein, we present a catalyst‐free, one‐pot hydrothermal oxidation strategy for the efficient upcycling of waste PE into high‐value oxidized polyethylene wax (OPEW). Notably, under optimized conditions (160°C, 1.5 MPa O 2 ), low‐density polyethylene (LDPE, 1.0 g) is converted to OPEW within 0.5 h, achieving an OPEW/PE mass ratio of 103.3% and a carbon yield of 99.8%. The resulting OPEW exhibits a tunable acid number (20–70 mg KOH/g) and saponification number (5–80 mg KOH/g), covering industrial specifications for commercial wax products. Mechanistic studies reveal that the superoxide radical (·O 2 − ) plays a key role in mediating the reaction. Furthermore, 30‐fold scale‐up trials and successful application to various types of PE waste feedstocks demonstrate the great potential of this methodology for industrial viability. This strategy establishes a sustainable, catalyst‐free pathway for upcycling plastic waste into functional materials.

Light‐Driven Epimerization: Diastereoconvergent Synthesis of [ ¹² C, ¹³ C] <i>β</i> ^2,3 ‐Amino Acids

ABSTRACT β ‐Amino acids are crucial building blocks for bioactive peptides and pharmaceuticals, wherein the stereochemistry of C 2 , C 3 ‐disubstituted β 2,3 ‐amino acids dictates the secondary structure of β ‐peptides. However, the diastereoselective synthesis of these scaffolds remains a formidable challenge. Herein, we report a novel photocatalytic cascade enabling the one‐pot hydrogenation, carboxylation, and epimerization of α , β ‐unsaturated imines. This method provides direct and highly diastereoselective (d.r. up to 35:1) access to valuable syn ‐ β 2,3 ‐amino acids. Time‐course analysis and DFT calculations reveal a unique light‐driven dynamic kinetic epimerization process that ensures stereoconvergence to the thermodynamically favored syn ‐isomer. Notably, this strategy also facilitates the facile synthesis of 13 C‐labeled syn ‐ β 2,3 ‐amino acids using commercially available 13 C‐sodium formate, achieving exceptional isotope incorporation (93%–98%) that surpasses existing 13 CO 2 ‐based methods. Furthermore, the system's utility is demonstrated through the gram‐scale synthesis of N‐unprotected α ‐amino acids from imines (11 g, 75% yield), more significantly, via a one‐pot procedure directly from diaryl ketones.

“Two‐in‐One” Anion Engineering Strategy for One‐Step Ethylene Purification From a Ternary Mixture

ABSTRACT One‐step purification of C 2 H 4 from a C 2 H 2 /CO 2 /C 2 H 4 mixture represents a significant industrial challenge. However, conventional ligand engineering strategies struggle to simultaneously enhance adsorption capacity and separation selectivity. Herein, we present an innovative “two‐in‐one” anion engineering strategy involving the substitution of SiF 6 2− with ZrF 6 2− , which enhances CO 2 capture while effectively shields C 2 H 4 adsorption at the fluorine sites. Compared to SIFSIX‑1‑Cu‑(CH 3 ) 2 , ZrFSIX‑1‑Cu‑(CH 3 ) 2 exhibits a dramatically enhanced CO 2 uptake (from 35.3 to 87.3 cm 3 /g). More importantly, the adsorption preference shifts from C 2 H 4 ‐selective to CO 2 ‐selective, with the CO 2 /C 2 H 4 (50/50) ideal adsorbed solution theory (IAST) selectivity increasing from 0.59 to 1.66. Dynamic breakthrough experiments demonstrate the exceptional separation performance of ZrFSIX‑1‑Cu‑(CH 3 ) 2 for a C 2 H 2 /CO 2 /C 2 H 4 (1/9/90) mixture. Theoretical calculations reveal that the highly electronegative F atoms on the ZrF 6 2− anions enhance the interactions with CO 2 , while ligand rotation‐induced pore contraction and methyl steric effects act synergistically to hinder C 2 H 4 from accessing the fluorine sites. This study provides a new paradigm for the design of materials aimed at purifying C 2 H 4 from multi‐component mixtures.