Journal of Materials Chemistry C最新文献

MAX phases (M _n+1AX _n ), precursors to MXenes, span a vast compositional space, motivating efficient computational screening for synthesisable candidates. We employ CrystaLLM-π, a large language model fine-tuned on 6179 double transition-metal MAX phases, and demonstrate its ability to generate novel structures consistent with known experimental trends. Using a conditioning vector with two dimensions (a statistically derived MXene derivative count and a surrogate for A-site binding energy), the model was able to target MXene-favourable regions of phase space for generation. Specific condition vectors double novel stable structure generation rates versus unconditioned baselines. Of ten compositionally novel candidates, five exhibit DFT-validated (meta)stability (E _hull < 0.050 eV per atom). This work showcases the potential for autoregressive generative models to explore targeted materials' spaces, offering a scalable framework for accelerated discovery in compositionally complex systems.

There has been uncertainty for several decades over the crystal chemistry, composition and thermodynamic stability of the nominally stoichiometric tetragonal tungsten bronze (TTB), Sr₂NaNb₅O₁₅ (SNN). Recent interest in SNN-based ceramics sintered at ≥1300 °C has come about because of their high permittivity over a wide temperature range making them attractive for 'next generation', high temperature class II multi-layer ceramic capacitors. Here we use a solid-state reaction method between NaNbO₃ and SrNb₂O₆ powders in a 1 : 2 mol ratio to verify this SNN-based TTB is not thermodynamically stable below ∼1200 °C. Instead, a mixture of A-site deficient Sr-doped NaNbO₃ perovskite (i.e. Na_1-2x Sr _x NbO₃ with x ∼ 0.20) and SrNb₂O₆ is obtained. We confirm the thermal instability of an A-site deficient SNN by demonstrating its complete decomposition to the same biphasic mixture at 900 °C by in situ powder X-ray diffraction. The local bonding arrangements and co-ordination number (CN) of the A-site cations created by the NbO₆ octahedral arrangements play a crucial role in the thermodynamics of this system. For Sr-doped NaNbO₃, there is a random arrangement of Na⁺, Sr²⁺ ions and vacancies on the A sites with CN < 12 in a perovskite lattice of corner sharing NbO₆ octahedra. For SrNb₂O₆, the Sr²⁺ ions are in a corrugated arrangement along channels with CN = 8 based on a lattice of corner sharing Nb₂O₁₀ dimers. This phase assemblage is energetically more favourable below ∼1200 °C than Sr²⁺ and Na⁺ ions on A1 (CN = 12) and larger A2 (CN = 15) sites within a TTB lattice based on corner sharing NbO₆ octahedra. The thermodynamic instability of the TTB-SNN below ∼1200 °C has similarities to that for the metastable TTB-PbNb₂O₆ and has implications for the dielectric applications of SNN ceramics.

Ultrafast scintillators based on ternary hexafluorides are promising for next-generation radiation detectors, which can be used in time-of-flight positron emission tomography. To gain a detailed understanding of the scintillation mechanism in these materials, accurate knowledge of the electronic band structure is required. In this study, photoelectron spectroscopy, density-functional theory, and G₀W₀ calculations were used to investigate the electronic structure of K₂SiF₆. The G₀W₀ calculations predict a wide band gap of 12.4 eV reflecting the strongly ionic character of the bonding. In contrast to predictions from semi-local or hybrid density-functional theory calculations, the large band gap predicted by G₀W₀ suggests that Auger-Meitner decay of K 3p holes is energetically not allowed and that scintillation via cross-luminescence is possible in this material. However, the poor light-yield observed experimentally indicates that the exclusion of Auger-Meitner decay is not sufficient for good scintillation performance, and cross-luminescence competes with other decay channels.

The study provides guidance for developing doping-free white organic light-emitting diodes (OLEDs) with single or double light-emitting layers and offers insights into molecular structure-property relationships for highly efficient dimethoxybenzothiadiazole-based emitters. To achieve white electroluminescence, newly synthesised dimethoxybenzothiadiazole derivatives were used as red fluorescent emitters in combination with emitters exhibiting efficient thermally activated delayed fluorescence (TADF), such as a sky-blue exciplex emitter or a conventional green emitter. The developed compounds exhibit photoluminescence quantum efficiencies of up to 98% in solutions, hole mobilities exceeding 1 × 10^-4 cm² V^-1 s^-1 at electric fields above 1 × 10⁶ V cm^-1, ionisation energies of ca. 5.6 eV, and electron affinities of ca. 3.4 eV. These properties enabled us to fabricate doping-free OLEDs with an external quantum efficiency (EQE) of up to 3.34% and red electroluminescence with CIE1931 (x, y) colour coordinates (0.54, 0.36). The sky-blue exciplex-based TADF emitter tunes the colour coordinates and enhances EQE by up to 8.5%. The green TADF emitter enabled us to achieve stable warm-white electroluminescence in OLEDs with double, fully doping-free light-emitting layers, exhibiting EQE up to 8.23%, and colour coordinates of x up to 0.43, and y up to 0.38.

In this work, we have prepared magnetite nanoparticles (MNPs) coated with polyethylenimine (PEI) to obtain a positively charged surface and showed their suitability as functional supports to successfully immobilize glucose oxidase (GOx) and catalase (CAT) enzymes. We have compared two immobilization strategies, namely electrostatic binding and covalent attachment mediated by glutaraldehyde cross-linking. To quantify the amount of immobilized enzyme (q _max), we have developed a methodological approach that minimizes the dependence of the q _max value on the equilibrium constant of the adsorption process (K). Catalytic studies showed high retention of enzymatic activity (100% for covalent binding and 75% for electrostatic binding), indicating that the immobilization protocol preserves the native conformation of the enzyme. Furthermore, the covalent strategy demonstrated stable binding even when the nanohybrid was subjected to extreme conditions (pH 3), retaining 91% of the enzyme on the surface, compared to 6% when immobilized electrostatically. These results highlight the importance of surface engineering in the design of magnetic biocatalysts for potential application in starvation or oxygen generation therapies.

Hierarchical ordering is common in Nature, where materials are organised in specific architectures across multiple scales, to achieve function-led design. Herein, we demonstrate multi-tiered organisation of silica nanoparticles (NPs), within a nanocomposite by employing direct laser writing (DLW). The hierarchical arrangement was optimised for wide-gamut reflected colour across the visible range by controlling NP size, NP type (core-shell and core-only), NP volume, and DLW fabrication parameters. The obtained microstructures were characterised using SEM, demonstrating retained order of non-close-packed NPs, and reproducible high-resolution fabrication with sub-micron features. We further used microspectroscopy to quantify the effect of fabrication parameters on structural colour, which is supported by FIB-SEM analysis, and exploited this effect to fabricate 3-dimensional multi-coloured images at the micro-scale. We demonstrate that this process can also be expanded to fabricate photonic nanocomposite microstructures using plasmonic core-shell NPs.

An essential prerequisite for the efficient functioning of semiconductor devices is the optimal charge transfer between electrodes and organic active regions. With the design of molecules and the upgrading of devices, there has been rapid development in hole-injection materials (HIMs) and their applications, which offer distinct advantages such as higher hole-injection efficiency, better interface stability, and broader process compatibility. However, they face several scientific challenges. The interface may still suffer from Schottky barriers due to slight energy-level mismatches or surface roughness, negatively impacting the device efficiency. Additionally, the corrosive effects of the processing solvent at the material interface can affect the device lifespan. More importantly, the challenges in achieving proper energy-level alignment and the trade-off between molecular hole mobility and device structure must be addressed. This review primarily discusses different types of hole-injection materials used in various organic optoelectronic devices, summarizes their latest developments and applications, and discusses the challenges and issues that need to be overcome in the future development of this field.

Mental health problems are closely linked to imbalances in neurotransmitters, with dopamine serving as a critical biomarker for early diagnosis of mental health disorders. Conventional detection methods are often limited by complex instrumentation, poor selectivity, and a lack of real-time capability. Wearable sensors have emerged as a promising solution, offering real-time, non-invasive monitoring of dopamine and other neurotransmitters, which play key roles in the regulation of mental health. The performance of these sensors is highly influenced by the properties of the active materials used in their fabrication. Among emerging materials, two-dimensional transition metal dichalcogenides (2D TMDs) have garnered significant attention due to their distinctive physicochemical properties, including high surface area, tunable electronic structure, and excellent electrocatalytic activity. In this review, we discuss recent developments in 2D TMD-based dopamine detection, covering synthesis approaches, structure–property relationships, and their implementation in electrochemical, optical, and field-effect transistor sensors. We especially emphasize performance benchmarking against conventional materials, highlighting the advances in sensitivity, selectivity, and miniaturization of 2D TMDs-based sensors for dopamine detection. We also discuss the current challenges while outlining future directions in this research domain. By integrating materials science with biomedical needs, this review highlights the potential of 2D TMDs to enable next-generation neurochemical monitoring technologies.

Reaching extremely high levels of sophistication of naturally occurring supramolecular polymers (SPs) with artificial structures represents a paradigm with important underlying application potential in various fields such as biomaterials and optoelectronics. A key challenge in synthetic SP research is mimicking the complex hierarchical and multiple level folding of natural SPs, such as DNA for instance. In previous works, we have developed an artificial mimic of the chlorosome pigment antenna, consisting of micrometer-long phenanthrene-based SP nanofibers, with exceptional light-harvesting properties. In the present work, we have advanced this system one step further, by assembling the Trimer A nanofibers into sophisticated hierarchical nanostructures. To our knowledge, this work is the first report of hierarchical nanostructures of a functional synthetic SP. The polymerization was monitored by means of UV/visible and fluorescence spectroscopy. Cryo-EM and AFM revealed high aspect-ratio nanoribbons as well as large annular nanostructures. Our thorough study with acridine orange as the energy acceptor shows that the excellent light-harvesting antenna effect is preserved. The annular nanostructures observed are unprecedented in the field of synthetic hierarchical SPs, and this constitutes a notable chemical achievement. We also report the first calculation of a dimensionality compression factor, and we found a remarkable two-orders-of-magnitude reduction for an annular structure. Overall, the present work shows that dimensional compression does not impede light-harvesting performance. It paves the way, in SP science, for potential applications such as advanced energy materials.

Organic–inorganic hybrid perovskite materials demonstrate significant potential in photodetection due to their outstanding optoelectronic properties. However, their inherent structural characteristics result in limited light response in the ultraviolet and near-infrared bands (>800 nm), severely limiting their applications in multiband imaging, optical communications, and biomedical detection. This study extended the spectral response range of devices from the ultraviolet to the short-wave infrared region (1000–1600 nm) by constructing a heterojunction structure between PbS colloidal quantum dots (CQDs) and FA_0.9Cs_0.1PbI₃ perovskite (PSK) thin films. The results indicate that a Type-II band alignment at the PbS/perovskite heterojunction interface promotes efficient separation and transport of photo-generated carriers. The fabricated ITO/SnO₂/PbS/FA_0.9Cs_0.1PbI₃/Au device achieved responsivities of 82.5 mA W⁻¹ at 280 nm (UV), 319.3 mA W⁻¹ at 520 nm (visible), and 63.3 mA W⁻¹ at 1550 nm (near-IR), with specific detectivities (D*) of 4.3 × 10¹⁰, 1.7 × 10¹¹, and 3.3 × 10¹², respectively. This heterojunction detector exhibits fast response characteristics (rise/fall time: 160 ms/80 ms) under a 0.6 V bias. This study provides a novel material system and device design strategy for developing high-performance, low-cost multiband photodetectors.