ACS Materials Letters最新文献

The influence of hard and soft base coordination on ionic conductivity was systematically investigated using diamine (hard base)- and dinitrile (soft base)-based ligands in molecular crystal-based solid electrolytes. For molecular crystals (Gln)₂LiPF₆, (Gln)₂CuPF₆, (DAB)₂LiPF₆, and (DAB)₂CuPF₆ (Gln = glutaronitrile, DAB = 1,4-diaminobutane) with isomorphic crystal structures (P4̅2₁c space group) and comparable metal–metal (Li⁺–Li⁺ or Cu⁺–Cu⁺) distances, less favorable soft–hard interactions (Cu⁺–amine or Li⁺–nitrile) resulted in nearly 2 orders of magnitude improvement in ionic conductivity compared to the more favorable soft–soft and hard–hard pairings (Cu⁺–nitrile or Li⁺–amine). This significant enhancement is attributed to the weaker, more labile coordination between soft nitrile donors and hard Li⁺ ions or hard -NH₂ donors and soft Cu⁺, facilitating faster ion migration, reinforcing the critical role of Hard–Soft Acid–Base theory (HSAB)-guided coordination chemistry in modulating ion mobility in soft-solid molecular electrolytes, and providing valuable insights to rationally design high-performance solid electrolytes.

Realizing organic materials that exhibit a dynamic thermal conductivity requires a fundamental understanding of how molecular structure and processing affect thermal transport. Herein, we demonstrate that the photoinduced polymerization of [2,2′-bi-1H-indene]-1,1′-dione-3,3′-diheptylcarboxylate (BIT) into polyBIT results in over a 4-fold decrease in thermal conductivity as measured on polycrystalline thin-films in the through-plane direction, mostly perpendicular to the chain growth direction. Experimental determination of the material’s decreased heat capacity supports this view. Through theoretical calculations, we attribute this decrease in thermal conductivity in part to induced anisotropy in the polymer. We also discuss the non-negligible changes in morphology, phase transitions, and thermal degradation that serve to limit the thermal depolymerization reaction. This work highlights the different contributions one must consider when designing an organic thermal switch that operates in the solid-state.

The atomic thinness and mechanical flexibility of two-dimensional (2D) transition metal dichalcogenides (TMDs) make strain engineering a powerful strategy for tailoring their functional properties. Nevertheless, conventional strain-engineering methods often suffer from limited spatial control and unwanted sample damage. Here, we report a controlled synthesis of monolayer WS₂ with programmable localized strain via a sulfur-rich chemical vapor deposition approach. Atomic-resolution scanning transmission electron microscopy reveals varying degrees of atomic-level local strain, which lead to significant suppression of Raman, photoluminescence, and second-harmonic generation spectral intensities. Furthermore, piezoresponse force microscopy measurements demonstrate a characteristic butterfly-shaped amplitude loop accompanied by near-180° phase switching, indicative of robust ferroelectric behavior. Consistent hysteresis observed in vertical device architectures further confirms the emergence of out-of-plane ferroelectricity. Our work introduces a scalable, damage-free route to create tailored strain landscapes in monolayer TMDs, thereby opening avenues for property control in 2D semiconductors and enabling the design of multifunctional devices.

The need for sustainable, high-performance, and recyclable materials is growing, but biobased polymers often lack the necessary durability and functionality. Here, we report a class of biobased, metal-coordinated polyimine vitrimers (MCPVs) engineered through dual Fe³⁺ coordination sites (imine and methoxy groups) within a Schiff base network. The MCPVs achieved enhanced mechanical performance (tensile strength up to 25.6 MPa, toughness of 23.6 MJ/m³), thermal stability (>298 °C decomposition temperature), and acid/solvent resistance with only Fe³⁺ loading (5 mol %). The material retains closed-loop recyclability via hydrolysis with >99.9% antimicrobial efficacy against Escherichia coli and Staphylococcus aureus. Integrated with conductive layers, MCPVs enable fully recyclable wearable sensors for real-time motion detection, maintaining functionality after multiple recycling cycles. This work highlights a design strategy between sustainability and high performance, offering a scalable blueprint for circular-economy electronics and polymers.

Thermally evaporated perovskite light-emitting diodes (PeLEDs) offer high reproducibility and scalability, making them promising for next-generation displays. However, achieving spectrally stable pure-red mixed-halide PeLEDs that meet the Rec.2020 color standard remains challenging due to halide segregation and poor crystallinity. Here, we fabricated thermally evaporated pure-red PeLEDs by integrating 0D/3D Cs₄Pb(I_xBr_1–x)₆/CsPb(I_xBr_1–x)₃ heterostructures with a LiF interlayer. Excess CsI promotes 0D Cs₄Pb(I_xBr_1–x)₆ formation and lattice expansion, facilitating wavelength tunability and improved optoelectronic performance via defect passivation and enhanced exciton binding. The LiF interlayer further mitigates interfacial defects as F^– passivates undercoordinated Pb²⁺ and halide vacancies, while Li⁺ acts as a diffusion barrier to suppress halide migration, leading to reduced nonradiative recombination and excellent spectral stability. The optimized device achieves an EQE of 8.15%, luminance of 1786 cd/m², and T₅₀ lifetime of 234 min at 1 mA/cm². A 49 cm² perovskite film shows uniform photoluminescence, confirming excellent scalability for a commercial pure-red display.

Supramolecular chirality regulation by metal ions remains a fundamental challenge, yet the underlying molecular origins have been poorly understood. Herein, we report a combined experimental and theoretical study to unveil how metal ions dictate supramolecular chirality inversion in folate-based hydrogels. Folate-Cu²⁺ and Folate-Zn²⁺ are observed to display M- and P-form Cotton splitting, respectively. DFT calculations reveal that the coordination of Cu²⁺ and Zn²⁺ at the α-carboxylate headgroups of folate induces inversed folate conformation. Energy calculations demonstrate that the helical handedness of tetramer stacks is governed by interlayer coordination, as the P-form Folate-Zn²⁺ and the M-form Folate-Cu²⁺ tetramer stacks exhibit lower energy than their counterparts, respectively. This mechanism can be generalized to other metal ions (Ca²⁺, Pb²⁺, Mn²⁺, and Cd²⁺), where the supramolecular chirality of Folate-M²⁺ systems can be accurately predicted by DFT calculation. This work establishes a molecular-level picture for metal-ion-mediated chirality control, providing a predictive tool for rational design of chiral supramolecular materials.

This work reviews recent advances, key challenges, and future directions of semiconductor gas-sensing materials for dissolved gas analysis in transformer oil. It outlines the use of metal-oxide semiconductors, nanostructured materials such as two-dimensional materials and noble-metal-doped nanoparticles, and hybrid systems including MOF, MXene, and TMD for detecting critical fault gases such as hydrogen and acetylene, with emphasis on sensitivity, selectivity, and stability. It highlights progress achieved through surface modification, doping, defect engineering, micro-nano structural design, and plasma-based enhancement and considers the role of intelligent sensor systems and AI in material development and data interpretation. Despite improvements in low-concentration detection and response speed, issues remain in long-term stability, cross-sensitivity, and performance in complex oil environments. Future work should explore new material systems, establish unified testing standards, and integrate multidisciplinary approaches to enable efficient, intelligent transformer fault diagnosis. This review serves as a reference for designing semiconductor gas-sensing materials for power equipment monitoring.

Organic semiconductors (OSCs) are expected to play an important role in next-generation electronics due to their solution processability, etc. However, conjugated polymer films processed in solution usually have the problems of low crystallinity and carriers are easily trapped by semiconductor/dielectric layer interface traps, while solution processed small molecule OSCs films have poor integrity, both of which will lead to the damage of electrical properties. The vertical phase separation (VPS) of blend films of OSCs and insulating polymers (IPs) can solve these problems, improve the solution processability of small molecule OSCs, enhance the crystallinity of conjugated polymers, reduce interface traps, and significantly improve the performance of organic field-effect transistor (OFET). This review highlights key factors influencing the structural morphology of OSC/IP blend VPS films, and summarizes their applications in OFETs. Finally, challenges and opportunities for the preparation of multifunctional OFETs from OSC/IP blends are summarized and discussed.

The development of dynamic luminescent materials that are responsive to multiple stimuli is crucial for information security, but challenges still existing in material design. Herein, we employ an anionic metal–organic framework (MOF), denoted ZJU-64, as a photochemical reaction vessel to assemble two guests, a static energy donor (thioflavin T, ThT) and a photochromic dynamic energy acceptor (merocyanine, MC). The host–guest MC@ZJU-64 and MC&ThT@ZJU-64 materials exhibit reversible powder/fluorescence color switching under alternating exposure to visible light (470 nm) and heat (60 °C). Crucially, the well-defined nanopores not only suppress aggregation but also enable fluorescence resonance energy transfer from ThT to MC. This process can be modulated by light-induced MC isomerization, leading to a wavelength shift of about 200 nm. A proof-of-concept Morse code encryption platform is then demonstrated, where hidden information on different levels can be selectively revealed. This work provides a strategic design for creating smart responsive materials with high-level security functions.

Aqueous proton-coupled energy storage systems enable ultrafast charging and intrinsic safety in aqueous electrolytes, but the durable anodes operating at low potential (<0.3 V vs SHE) in acidic conditions are still challenging. This work introduces 1,6-poly(phenazine sulfide) (1,6-PPS), a functionally sulfur-bridged phenazine polymer anode designed to overcome key challenges. Its minimalist architecture enables exceptional stability in 1 M H₂SO₄, exhibiting near-zero capacity decay over 10,000 cycles. 1,6-PPS also delivers ultrafast kinetics, retaining 56% of theoretical capacity (141 mAh g^–1) at 50 A g^–1 due to extended π-conjugation and high proton diffusivity (5 × 10^–7 to 10^–9 cm² s^–1). The synthesis maximizes redox-active phenazine density, achieving a high specific capacity of 255 mAh g^–1. In a full cell with a N,N′-(2,5-dichloro-1,4-phenylene)bis(butane-1-sulfonamide) cathode, 1,6-PPS demonstrates a stable 0.77 V output and 96.4% capacity retention over 500 cycles. This work establishes sulfur-bridged phenazine polymers as durable, high-performance anodes for next-generation proton batteries.