Journal of Materials Chemistry C最新文献

With the increasing demand for high-density nonvolatile memory and in-memory computing, multilevel resistive switching has emerged as a promising strategy to enhance information storage density and computational capability. In this work, we present a multilevel resistive memory system based on a Pt/Ta/ZrO_x/Pt memristive device operated in a series-connected configuration with a transistor. All electrical characterization studies and resistive state modulations are conducted within this transistor-assisted framework, enabling precise current control and enhanced switching stability. The device exhibits robust and repeatable resistive switching, achieving six distinct low resistance states (LRS) and three high resistance states (HRS), with each demonstrating endurance over 3000 cycles and retention exceeding 10 000 seconds at room temperature. Furthermore, by finely tuning the gate voltage of the transistor, at least 11 well-separated programmable resistance levels are realized through arbitrary programming sequences. These results underscore the potential of the proposed system for multibit memory and neuromorphic computing applications, where reliable multistate operation is critical.

Flexible perovskite solar cells (F-PSCs) have emerged as a transformative photovoltaic technology with exceptional power conversion efficiencies exceeding 25%, lightweight nature, and compatibility with roll-to-roll manufacturing, yet their commercial deployment faces critical challenges due to insufficient mechanical stability under repetitive deformation. This review systematically examines the mechanical failure mechanisms in F-PSCs, including crack propagation, interfacial delamination, and electrode degradation, which are exacerbated by synergistic interactions with environmental factors such as moisture, oxygen, and light. We comprehensively analyze recent advances in enhancing mechanical resilience through multifaceted strategies encompassing grain boundary engineering with low-dimensional phases and molecular additives, interface engineering utilizing specialized monolayers and polymer networks, and bioinspired structural designs informed by natural systems, which collectively mitigate stress concentration, strengthen interfacial adhesion, and enable superior damage tolerance in flexible perovskite photovoltaics. By integrating insights from material design to structural optimization, this review provides a comprehensive framework for addressing mechanical stability challenges in F-PSCs, advancing their potential applications in wearable electronics and portable power sources.

The electric field-induced antiferroelectric to ferroelectric transition in lead zirconate-based antiferroelectric materials has been explored for actuator, sensor and energy storage applications. The critical electric field required for the transition to the ferroelectric phase is the determining factor for the performance of antiferroelectric materials in practical applications. A way to decrease the critical electric field is chemical modification with isovalent (Ti⁴⁺) or donor (La³⁺, Nb⁵⁺) substituents. Here, we show that it is also possible with acceptors. We found this possibility while investigating Pb_0.995(Zr_0.53Sn_0.47−yTi_y)_0.99Nb_0.01O₃, with y = 0.07, a polycrystalline ceramic of typical antiferroelectric composition and its acceptor (Fe³⁺)-doped compositions. We closely examined its field-induced polarization switching as well as structural transitions. We found ferroelectric-like polarization switching at a particular acceptor concentration with a substantial reduction in critical electric field. We demonstrate that such unexpected ferroelectric-like switching in an antiferroelectric ceramic is brought about and regulated by point defects that are formed during the acceptor-doping as part of charge compensation.

Metal–organic frameworks (MOFs) represent a versatile class of materials with tunable physical properties, including magnetism. However, designing atomically precise, large-scale two-dimensional (2D) MOFs with strong magnetic coupling remains a major theoretical and experimental challenge. In this theoretical study, we investigate a novel 2D MOF structure based on biphenylene (BP) molecules coordinated with iron atoms (Fe–BP), using first-principles density functional theory (DFT) calculations. Our results reveal that the Fe–BP system exhibits a strong magnetic exchange interaction, with an exchange energy of approximately 233 meV, indicating robust ferromagnetic coupling. The system is predicted to be both ferromagnetic and half-metallic and displays a large magnetic anisotropy energy (MAE) of –47.81 meV, favoring in-plane magnetization. These magnetic properties originate from strong π–d electron interactions between the organic ligands and the iron centers. The calculations also suggest the presence of complex spin interactions beyond conventional superexchange mechanisms. This theoretical work highlights the potential of Fe–BP as a promising platform for two-dimensional metallic and ferromagnetic engineering due to its high magnetic stability. It also highlights its potential as a promising platform for high-temperature 2D spintronic applications due to its tunable magnetic and electronic properties.

In the pursuit of sustainable and efficient indoor agriculture, the development of advanced lighting technologies tailored to plant growth needs has become imperative. Conventional blue/near-UV LEDs with Eu²⁺/Ce³⁺ phosphors exhibit narrow emission, mismatching broad chlorophyll absorption in the 380–500 nm range and causing low light efficiency. Bi³⁺ phosphors offer broad emission and large Stokes shifts for reduced reabsorption; yet, their excessive bandwidth and poor thermal stability limit their utility. This study introduces an advancement in agricultural lighting technology through the development of a novel Cs₂MgSi₅O₁₂:Bi³⁺ blue-emitting phosphor, precisely regulated via K⁺ ion incorporation. The proposed material exhibits a broad emission band (FWHM = 95 nm) and a large Stokes shift (∼11 550 cm⁻¹), effectively mitigating spectral reabsorption while matching the wide absorption range of the photosynthetic pigment. The introduction of K⁺ ions not only enhances the thermal stability of the phosphor, achieving a thermal activation energy (ΔE) of 0.277 eV, but also enables the continuous tuning of the photoluminescence (PL) peak position between 380 and 405 nm by adjusting K⁺ doping concentrations. This dual modulation approach, combining Bi³⁺ doping with K⁺ regulation, demonstrates exceptional control over the luminescence properties, making the phosphor a promising and adaptable candidate for plant growth lighting requirements. Importantly, when encapsulated in LEDs, this phosphor significantly enhances the phenotypic characteristics of Brassica rapa var. pekinensis, underscoring its immense potential to advance indoor agricultural lighting systems.

We demonstrate a redox-switchable gelation system for unmodified cellulose nanocrystals (CNCs) driven by the oxidation of ferrocene (Fc). Upon oxidation of Fc to ferrocenium (Fc⁺), achieved either chemically or electrochemically, the increased ionic strength screens electrostatic repulsion between negatively charged CNC rods, thereby inducing physical gelation. The gel strength can be reversibly modulated: oxidation produces a strong gel, and subsequent reduction weakens it. Multiple redox cycles enable repeated switching, although complete recovery of the initial fluidity is not obtained. Rheological, spectroscopic, and electrochemical analyses confirm that the gelation arises from Fc⁺-mediated electrostatic screening without any chemical modification of CNCs. This simple, additive-driven strategy provides a sustainable platform for electro-responsive soft materials from renewable nanocrystals, with potential applications in drug delivery, microfluidic valves, and electro-assisted 3D printing.

The high hole mobility and layer-dependent properties of two-dimensional (2D) tin monoxide (SnO) make it a promising candidate for use as a channel material in field effect transistors. However, the widely used top contact (TC) configuration in such transistors often faces high contact resistance due to weak van der Waals interaction at the interface. In contrast, the edge contact (EC) configuration offers improved charge injection efficiency through chemical bonding at the interface. This study provides a comprehensive investigation of the electronic properties of monolayer (ML) and bilayer (BL) SnO ECs with different metal electrodes (silver, aluminium, gold, copper, and nickel) via first-principles calculations. Our results show that SnO undergoes clear metallisation at the edge. Tunnelling barriers (TBs) are found within ML SnO instead of at the metal–semiconductor interface, whereas they are eliminated in BL SnO. Schottky barriers (SBs) are also observed near the TB locations. Metallisation is confined to Sn and O atoms near the interface, while distant regions remain semiconducting. The calculated Fermi level pinning factor for ML SnO ECs is 0.48, which is higher than the mean (0.31) and median (0.28) values reported in theoretical studies of ECs and TCs of 2D semiconductors. The carrier mobilities of BL SnO under ECs appear to be higher than those of its ML counterpart, as indicated by the more dispersive band structures of the former. This behaviour is likely attributed to the intrinsic layer-dependent properties of SnO. These findings offer robust guidance for the design of SnO-based EC transistors.

Solution-processing of thin-film photovoltaics offers an alternative to vacuum-deposition based approaches. The amine–thiol reactive solvent system has become a focal point for the solution-processing of chalcogenide species, owing to the convenience of precursor preparation and comparatively high performance of prepared devices. Selenide species prepared via the amine–thiol route typically progress through a sulfide intermediate phase, and as such are commonly afflicted with sulfur and carbon impurities along- side the presence of a carbonaceous fine-grained layer. Here, two routes of preparing films directly to a selenide phase are examined; first by the co-dissolution of selenium in an amine–thiol solution and second via the novel use of reactive alkylammonium polyselenides. Lamella are cut from these selenide precursor films and final devices, and STEM-EDX and TEM are used to characterize film morphology and secondary phases. A champion device efficiency of 11.2% is reported for the novel polyselenide route, and clear paths of improvement are identified.

In this paper, a type of multilayered chiral metastructure-photonic crystal (MCMPC) is proposed to investigate the absorption properties of circularly polarized waves in the near-infrared regime. The MCMPC consists of three metastructure-photonic crystal (MPC) units separated by two air spacers, including metallic silver, tungsten, air, silicon dioxide and an isotropic dielectric material. The absorption of right-handed circularly polarized (RCP) waves reaches nearly 0.96 in forward propagation, whereas left-handed circularly polarized (LCP) waves maintain absorption below 0.3 under identical incidence. Therefore, the configuration demonstrates strong circular dichroism (CD) with a peak value of 0.78 at 332 terahertz (THz), resulting in distinct polarization-selective absorption responses. The results were interpreted through electric field energy density distributions to elucidate the working mechanisms. Remarkably, the chiral multilayer configuration enables a relative bandwidth of 16.2% for forward RCP wave absorption above 0.9 while suppressing backward absorption below 0.19. The operating bandwidth spans 312–367 THz, achieving a peak value of the asymmetric absorption coefficient (difference between forward and backward RCP wave absorption) of 0.79 at 327 THz. In addition, the influences of the inclination angle and vertical height of the layers in the MPC units, along with external variables such as the incident angle and polarization angle, are investigated in detail. Thus, the proposed MCMPC resolves the fundamental challenge of the concurrent realization of intense CD, broadband functionality, and asymmetric absorption in chiral systems, which holds important potential for advanced polarization-selective devices in integrated photonic platforms.

Owing to its high process compatibility and exceptionally high dielectric constant (k) at zero bias, the HfO₂–ZrO₂ solid solution near the morphotropic phase boundary (MPB) has been extensively investigated as a promising dielectric material for next-generation dynamic random-access memory (DRAM) capacitors. Despite significant research efforts to apply MPB thin films to DRAM capacitors, conventional electrical characterization methods have critical limitations. Specifically, while the typical operating voltage of DRAM capacitors is approximately 0.8 V, most prior studies have evaluated dielectric properties at considerably higher voltage ranges, leading to substantial overestimation of capacitance. In this study, we systematically investigated the dielectric properties of MPB thin films within a voltage range of 0.5 V, closely aligned with practical DRAM capacitor operating conditions, and clarified the origin of capacitance overestimation. By employing two consecutive low-voltage sweeps, we suppressed two major sources of capacitance overestimation (dynamic and extrinsic components), enabling the accurate evaluation of feasible k-values relevant to DRAM applications. Furthermore, first-order reversal-curve measurements revealed a correlation between domain configurations and dielectric performance. Notably, the optimal composition for maximising the k-value differed between the low- and high-voltage measurement regimes. These findings demonstrate that preventing capacitance overestimation and optimising the composition to control domain configurations are critical steps toward the reliable implementation of MPB thin films in next-generation DRAM devices.