Materials Horizons最新文献

Nonconventional luminophores have gained significant attention for their distinctive luminescence behaviors and promising applications. However, achieving precise control over their photoluminescence (PL) remains a substantial challenge. Current strategies for structural modification remain largely semi-empirical, lacking robust frameworks to effectively correlate molecular-level variations with aggregate states and their corresponding PL. In this study, we demonstrate tunable full-color emission (blue to red) with a high quantum yield of up to 58.9%, through site-selective thiolation of hydantoin (HA) and subsequent host-guest doping. We elucidate the thionation effect on both individual molecules and their molecular arrangements, revealing that CS groups and parallel molecular arrangement promote extensive electron delocalization and redshifted PL. Leveraging the structural and packing similarity between the host and guest, we achieve fine-tuning of PL by doping thionated molecules into HA and thiazolidinedione crystals, establishing a direct structure-property relationship without requiring complex molecular redesign. Furthermore, we showcase the applicability of these luminophores in advanced anti-counterfeiting, information encryption and high-resolution visualization of latent fingerprints. This research offers novel insights and broadly applicable strategies for achieving tunable emission in nonconventional luminophores by precisely controlling electronic structures and molecular arrangement.

Organic photonics is a vibrant research field that harnesses the unique optical properties of organic small molecules and polymers, offering significant potential for applications in displays, sensors, and quantum communication. However, single-component materials are increasingly inadequate for meeting the demands of complex optical functionalities. In this study, we have fabricated organic branched heterostructures (OBHs) via a sequential process combining lattice-matched epitaxial growth and controlled stepwise crystallization. The structure consists of a laser gain medium as the main chain, with branches made from energy receptor molecules that possess efficient waveguide properties. The excitation dipole moments between the main chain and the branches are aligned at a fixed, well-defined angle, enabling the integration of organic laser materials with complex waveguide functions while maintaining excellent polarization retention properties. Under circularly polarized light excitation, the heterostructure demonstrates remarkable circularly polarized laser emission (|g_lum| = 0.05) from the trunk and chiral transmission (|g_lum| = 0.03) to the branch. Our work demonstrates that the rational design of OBH structures provides an innovative strategy for circularly polarized laser design and opens new avenues for research in chiral photonic chips.

In this study, we have systematically modulated the intersystem crossing/reverse intersystem crossing (ISC/RISC) competition in organic molecules (PhODCB, PhSDCB and PhSeDCB) with a D-A-D configuration to achieve emission from fluorescence to thermally activated delayed fluorescence (TADF) and then to room-temperature phosphorescence (RTP) by incorporating the chalcogen atoms oxygen (O), sulfur (S) and selenium (Se), respectively. Their distinct photophysical behaviors can be ascribed to both the enhanced heavy-atom effect and n → π* transition from O to Se atoms, which can enhance the quantum yield and effectively promote radiative decay of the triplet excited states to the ground state. Notably, with o-carborane as a strong electron acceptor, PhSeDCB can represent an unprecedented red-emitting RTP molecule with a very impressive photoluminescence quantum yield (PLQY) of 0.48 and a short lifetime of 14.7 µs. In addition, the first red organic light-emitting diodes (OLEDs) prepared with PhSeDCB show a high electroluminescence efficiency of 18.9%. All these encouraging results have indicated the great potential of metal-free phosphorescent materials in the field of OLEDs.

This study presents the fabrication of tungsten oxide-tungsten disulfide, h-WO₃/2H-WS₂ (WS_xO_y), and its integration on the nanostructured diatomaceous earth (DE) microalgae surface to obtain a novel photocatalyst known as DE-h-WO₃/2H-WS₂ (DE-WS_xO_y) for the first time. It is significant to mention that the integration of WS_xO_y on the DE surface is directed toward enhancing the overall photocatalytic properties and performances. The developed novel photocatalyst is characterized using various techniques to study its morphological surface chemistry features, interface interactions and photochemical properties. The novelty of this study lies in the synthesis of a new photocatalyst integrated with microalgae, enabling rapid and high-performance solar-driven degradation. Importantly, through the support of the DE surface, the photocatalyst exhibits higher photocatalytic ability in aqueous phase reactions when compared with WS_xO_y alone, which could be due to synergistic effects such as higher adsorption properties, dispersibility, stability and more catalytic reaction sites. Furthermore, using rhodamine B (Rh B) as a model pollutant, the designed photocatalyst validated with 99.8% of decoloration efficiency was achieved. The prepared photocatalyst exhibits excellent photocatalytic degradation efficiency under various solution conditions for multiple dyes and mixed dye solutions, demonstrating its potential industrial significance. Besides, this work expanded towards investigating its photocatalytic reaction mechanisms and factors affecting photocatalytic activities. As a proof of concept/pioneering technology, the DE-WS_xO_y photocatalyst was integrated with PDMS in the form of easily adaptable discs to explore the real-time photodegradation of industrial wastewater (IWW), which can be regarded as next-generation photocatalyst development.

Wearable temperature sensors are essential for medical and personal thermal management applications but often face challenges in achieving accuracy, flexibility and multifunctionality. To address these limitations, we developed a biodegradable polymer-based quaternary composite that leverages a binary eutectic fatty acid system and graphene nanoplatelets (GNPs) to deliver self-regulating heating and temperature sensing capabilities. The incorporation of polycaprolactone (PCL), lauric acid (LA) and myristic acid (MA) facilitates precise thermal control by enabling a tuneable phase transition range of 30 to 60 °C, while GNPs enhance electrical conductivity and thermal response. Notably, the material exhibits a distinct double positive temperature coefficient (PTC) effect, maintaining PTC behaviour up to 80 °C without transitioning to a negative temperature coefficient (NTC) effect. This double PTC behaviour enables precise thermal regulation, with self-regulating heating at ∼36 °C under low-power operation (∼100-250 mW), demonstrating stable power consumption and effective heat absorption through its phase change properties. The composite also supports operation under practical voltages, 5 V (standard power bank), making it well-suited for wearable systems. Additionally, the material demonstrates excellent recyclability through a simple dissolution and recasting process, retaining its stable thermal response even after recycling. These attributes make the composite highly suitable for electronic skins, smart thermal regulation and overcurrent protection fuses. The integration of PCL and fatty acids (FAs) enhances recyclability, promoting sustainable and long-term applications in personal thermal management systems.

The global pursuit of carbon neutrality demands transformative clean energy solutions, with advanced energy storage materials at the forefront. Metal-organic frameworks (MOFs), owing to their tunable porosity, ultrahigh surface areas, and adaptable physicochemical properties, have rapidly risen as promising building blocks for next-generation electrochemical energy storage. Beyond pristine MOFs, engineered composites and derivatives now showcase remarkable multifunctionality, enabling improved performance in diverse battery systems. Despite this progress, significant barriers remain in translating laboratory success into practical deployment. This review provides a systematic overview of recent advances in MOF-based materials, highlighting their evolving roles as electrodes and separators in Li/Na/K-ion, Li/Na/K-S, and Zn-ion batteries. We classify design strategies by battery type, critically assess electrochemical performance, and dissect the structure-property-function relationships that underpin device operation. Finally, we outline the central challenges-stability, scalability, and interface engineering-while offering forward-looking perspectives on how to bridge these gaps. By integrating state-of-the-art progress with future opportunities, this review seeks to inspire innovative material design and accelerate the realization of sustainable MOF-based energy storage technologies.

Niobium oxide (NbO_x)-based threshold switching memristors (TSMs) demonstrate significant promise for hardware implementation of neuromorphic computing, but their threshold stability's susceptibility to external environmental variations remains unclear. This work elucidates the switching mechanism in an NbO_x-TSM incorporating a low-thermal-conductivity CdTe₂ interlayer, which operates via the Poole-Frenkel (PF) emission model. Our investigation reveals that a double interlayer structure yields the highest effective thermal resistance, thereby most effectively reducing the threshold voltage. By implementing this structure, we enhanced the switching stability by 30.9%. Furthermore, increasing the thickness of the double-sided interlayers from 3 nm to 9 nm improved the stability by an additional 24.7% while simultaneously lowering the threshold voltage. The impact of the interlayer thickness on oscillatory behavior was systematically analyzed within a leaky integrate-and-fire (LIF) neuron circuit, where the observed frequency saturation phenomenon provides critical guidance for thermal engineering design. Capitalizing on these findings, we developed a multimodal, integrated memristor-based system for electrocardiogram (ECG) arrhythmia detection that leverages device thickness and temperature characteristics to achieve a classification accuracy rate of 90.0%. This work underscores the significant value of such physically interpretable devices for the hardware realization of neuromorphic computing.

Efficiency roll-off at high luminance is a significant issue in organic light-emitting diodes (OLEDs) made using thermally activated delayed fluorescence (TADF) emitters. It is often attributed to singlet-triplet annihilation (STA) or triplet-triplet annihilation (TTA) in the light-emitting layer, but their contributions are not properly quantified because of uncertainty about the magnitude of the rate constants. Here we show that a combination of time-resolved photoluminescence (PL) measurements with variable pulse repetition rate and with background illumination provides a reliable method to study STA and TTA. We find that the STA rate constant in a multi-resonant TADF emitter DABNA-2 dispersed in mCBP increases from about 3 × 10^-11 to 1 × 10^-10 cm³ s^-1 with increasing emitter concentration from 3 to 10 wt%. The rate constant for TTA in the film with 10 wt% of DABNA-2 is four orders of magnitude smaller than that for STA and below the sensitivity limit at lower concentration of DABNA-2. Modelling of the OLED efficiency roll-off with experimentally determined parameters shows that STA is responsible for more than half of the efficiency loss at high luminance in the device with this emitter, whilst TTA can slightly reduce the effect of STA. The combination of these measurements and modelling is a powerful tool that can be employed for selecting the optimal host material for a particular emitter and the emitter concentration to minimize efficiency roll-off.

Designing functional sites with well-defined and directional photocatalytic activities is crucial for efficiently utilizing spatially separated photogenerated charge carriers and achieving high photocatalytic performance. Herein, inspired by natural photosynthesis, we successfully developed a series of phosphonic acid functionalized polyoxo-titanium clusters. We uncover the pivotal role of strategically positioning noncovalent interactions surrounding the catalytic center in regulating the CO₂ reduction performance. Remarkably, introducing amino groups in synergy with proton-rich phosphate moieties near the cobalt-nitrogen active site leads to a six-fold enhancement in photocatalytic CO₂ reduction activity. Among them, the modified cluster NH₂-BQTiCo delivers an exceptional CO₂ photoreduction performance under visible light, achieving a CO production rate as high as 1456 µmol g^-1 h^-1. Combining experimental results with DFT calculations reveals that strong intermolecular hydrogen-bonding traction around the catalytical center can significantly strengthen CO₂ adsorption and facilitate a smoother activation pathway. This work highlights a biomimetic design strategy to optimize electron delocalization within polyoxo-titanium clusters, thereby promoting efficient intramolecular charge transfer and advancing high-performance CO₂ photoreduction.

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