Journal of Materials Chemistry C最新文献

Semiconductor single-walled carbon nanotubes (s-SWCNTs) are a class of one-dimensional nanomaterials with unique structure and properties. Owing to their high conductivity and carrier mobility, s-SWCNTs are ideal materials for the fabrication of high-speed, low-power field-effect transistors (FETs) and other electronic components. Network s-SWCNTs are prone to electron scattering and local blocking, while array s-SWCNTs are highly ordered, providing a more direct and uniform charge transport channel, which is conducive to improving the performance of electronic devices. At present, the main methods for preparing s-SWCNT arrays are chemical vapor deposition (CVD) and post-treatment of synthesized CNTs. Herein, we discuss the principle, research progress, advantages and disadvantages of various methods for the preparation of s-SWCNTs and describe the properties of devices prepared by different methods, future research prospects and development directions.

Lead-free Cs₂AgBiBr₆ double perovskite solar cells (PSCs) possess unique environment-friendly and stable attributes. However, the wide bandgap of Cs₂AgBiBr₆ weakens the light capture capability, thus limiting the improvement in power conversion efficiency (PCE) for PSCs. Herein, a convenient and efficient method is presented by incorporating plasmonic Ag nanoparticles (NPs) onto a perovskite surface. Owing to the synergistic effect of far-field light scattering and near-field enhancement of Ag NPs, the short-circuit current density of the modified PSC is enhanced by approximately 30%. In addition, the introduction of Ag NPs endows a larger Fermi energy level difference between the TiO₂/perovskite interface, resulting in a higher open-circuit voltage. The optimized device with the structure of fluorine-doped tin oxide/compact TiO₂/mesoporous TiO₂/Cs₂AgBiBr₆/carbon delivers a PCE of 2.69% as compared to the control device with a PCE of 2.04%, which represents one of the highest efficiencies of hole transport layer-free, carbon-based PSCs. Furthermore, the unencapsulated device retains nearly 98% of its initial PCE even after being stored for 32 days at 25 °C and relative humidity of 40 ± 5%. This work provides a new insight into constructing high-efficient and environment-friendly PSCs.

Molecular solar thermal fuel (STF) systems harness solar energy from solar radiation and store it as chemical energy. The stored energy is released as heat in the presence of suitable stimuli. Recently, azobenzene and its several derivatives have largely been used to develop molecular solar thermal fuel systems. These molecules photoisomerize into a metastable state and store the solar energy. Various techniques are applied to tune the isomerization enthalpy, thermal back half-life and stability of the STF materials at the molecular level. In addition, the intermolecular assembly of the azo-molecules in an STF material plays an important role in altering the system's energy storage efficiency. A precise arrangement of photochromic compounds can be achieved by adjusting the chemical structures of the photoswitches, anchoring the photoswitches to a polymer/carbon-based material or attaching a phase-changing material to the photoswitches. These methodologies significantly alter the energy density and storage timing of the system. This review focuses on how suitable modulations of the molecular assembly nature of the photoswitches can be exploited to achieve highly efficient STF materials. Major factors, such as the structural design of the photochromes and different templating technologies, are addressed in detail. The proposed idea of tuning the molecular assembly in STF materials will provide rational guidance and facilitate the future development of efficient STF materials for large-scale applications in the field of renewable energy sources.

The development of ionic gel with high flexibility, wide operating temperature range, and excellent physicochemical stability is crucial for the next generation of wearable flexible strain sensors. In this study, a late-model ionic gel named MBTA–TBC was synthesized by click reaction using tri(2-mercapto ethyl)-1,3,5-benzenetricarbonamide (MBTA) as the cross-linking point, tri(2-methacryloyloxyethyl) borate (TBC) as the flexible chain, and bis(trifluoromethane) sulfonimide lithium salt (LiTFSI) as the ionic salt. During the polymerization process, MBTA liquid crystal small molecules will self-assemble to form cross-linking points of approximately 22 nm and anchor TBC flexible chains. Due to the mismatch in modulus between MBTA and TBC, distinctive fishnet-like microstructures with ion channels were formed spontaneously. The formation of ion channels promotes the transport of ions in the gel, and the fishnet microstructure is conducive to energy dissipation, thus enhancing the mechanical stability of the gel. The prepared ionic gel showed unique rheological properties, a high ionic conductivity of 4.1 × 10⁻⁴ mS cm⁻¹, a wide operating temperature range, and adhesive properties. As a flexible strain sensor, it exhibits high sensitivity (GF = 1.29), good linearity (R² = 0.9995), and excellent cyclic stability, and can respond to human joint bending and throat swallowing. The ionic gel shows potential application value in human health monitoring, artificial skin, and soft robots.

Aluminum gallium nitride (AlGaN)-based deep ultraviolet (DUV) light-emitting diodes (LEDs) hold tremendous potential and application prospects. However, DUV LEDs face challenges such as low internal quantum efficiency (IQE) and degraded luminous performance because of properties intrinsic to aluminum-rich group III-nitride materials. To address these challenges, traditional trial-and-error experimental methods are commonly employed. However, with rapid industrial advancements, this approach has become inadequate to meet current demands. In this work, this study demonstrates an effective approach to optimize the luminous performance of DUV LEDs using machine learning (ML). By training 4 typical ML models with a dataset of AlGaN-based LED structures compiled over the past decade and more, we find that the convolutional neural network (CNN) provides the most accurate predictions, with a root mean square error (RMSE) of 1.6995 W cm⁻² and a coefficient of determination (R²) of 0.9812 for the light output power density (LOPD). Using the CNN model, we reveal the key features that influence the luminous performance of DUV LEDs. In addition, we explore the relationships between different features and LOPD, which align with physical mechanisms and are generally consistent with simulation and experimental results. Overall, this work demonstrates that ML is capable of predicting device performance, extracting critical features from complex structures, and significantly aiding in the optimization of DUV LEDs.

Two-dimensional (2D) van der Waals (vdW) stacking structures have gathered significant attention owing to their unique properties. The practical and large-scale applications of 2D materials in advanced technologies significantly hinge on the efficient transfer of chemical vapor deposition (CVD) synthesized 2D materials. However, this is hindered by issues such as contamination, limited materials compliance, and restricted scalability. To address these issues, we developed an effective transfer method using plasma-treated polyvinyl chloride (P-PVC) films and established a process for assembling vdW stack structures using a sequential pick-up procedure. Owing to the enhanced surface adhesion achieved using the plasma, P-PVC can overcome the strong adhesion between CVD-synthesized 2D materials and substrates. Consequently, P-PVC exhibited exceptional performance during the pick-up process with additional help of water delamination. The proposed method also showcases its advantages in the drop-off process, because the surface of P-PVC can act as a sacrificial layer that detaches from the PVC film along with the vdW structure. The P-PVC-based sequential pick-up approach not only mitigates interfacial contamination by polymer but can also play a vital role in facilitating efficient production and ensuring material compatibility. This technique offers significant potential for the physics and applications of vdW stacking structures.

This study focuses on hybrid magnetoelectric Ni₉₀Fe₁₀/BaTiO₃(011) heterostructures, which enable the control of the in-plane magnetization of the magnetostrictive layer through electric voltage. The heterostructure is both Pb- and rare-earth-free, thus enhancing environmental sustainability. We show that the BaTiO₃(011) orientation enables higher deformations in the piezoelectric regime compared to the commonly studied (001) orientation. In the as-grown state, the electrodeposited 200 nm-thick Ni₉₀Fe₁₀ film presents uniaxial in-plane anisotropy aligned with the [100] in-plane crystallographic direction of the BaTiO₃(011) substrate. X-ray magnetic circular dichroism photoemission electron microscopy images, along with hysteresis loops obtained by the magneto-optical Kerr effect, confirm the converse magnetoelectric coupling between Ni₉₀Fe₁₀ and BaTiO₃(011). The obtained converse magnetoelectric coupling constant of 0.205 μs m⁻¹ is significant considering it is achieved in the piezoelectric regime of the BaTiO₃ substrate and using an electrodeposited magnetostrictive film, making this heterostructure more viable for future applications. This value represents an increase of more than double compared to that previously reported for Ni/BTO(001) and, to the best of our knowledge, is the first value reported for the BTO(011) orientation.

Vat dyes represent an interesting class of building blocks for organic electronics as they are readily available at low cost and easy to functionalize. Yet, these molecules have never been used to prepare graphene nanoribbons (GNRs). Using the Brønsted acid-catalyzed alkyne benzannulation, two contorted GNRs have been synthesized from vat orange 1 and vat orange 3 in a few synthetic steps. These GNRs absorb light in the visible region with bandgap values around 2.0 eV and have been tested in organic field-effect transistors (OFETs) to measure their charge transport ability. Hole mobility values of up to 1.34 × 10⁻² cm² V⁻¹ s⁻¹ were measured in a bottom-gate top-contact device architecture.

The development of Bi³⁺-doped phosphors with outstanding luminescence properties is imperative because of their promising prospects for applications in near-ultraviolet LEDs. In this study, we have successfully obtained a high-quality Bi³⁺-doped CaLuGaO₄ blue phosphor via a high temperature solid-phase method. Bi³⁺ is found to be a substitute for both Ca²⁺ and Lu³⁺ sites within the crystal lattice, leading to a photoluminescence excitation spectrum that prominently displays two peaks at 335 nm and 370 nm, respectively. These peaks are well-aligned with the near-ultraviolet LED chips. Notably, CaLuGaO₄:0.004Bi³⁺ exhibits outstanding luminescence thermal stability, with the luminescence intensity at 420 K retaining a remarkable 76.7% of its value at 90 K. It is noteworthy that the luminescence intensity and thermal stability can be further enhanced through the incorporation of Al³⁺. The modified CaLuGa_0.7Al_0.3O₄:0.004Bi³⁺ phosphor exhibits exceptional performance, with its integrated emission intensity at 420 K reaching 91.8% of the room temperature value and an internal quantum efficiency of 60.8%. The PL spectra of CaLuGaO₄:Bi³⁺ match well with the blue regions of the absorption spectra for chlorophyll a and b, making it a viable candidate for applications in plant growth lighting. In addition, by combining CaLuGaO₄:Bi³⁺ with commercial red and green phosphors and utilizing 365 nm LED chips, a series of high-quality white light emitting diodes (w-LEDs) have been successfully produced. These w-LEDs boast a color rendering index (CRI) that exceeds 90, indicating promising prospects of CaLuGaO₄:Bi³⁺ phosphors in the development of high-quality w-LEDs powered by ultraviolet chips.

Aggregated anthracene derivatives typically display fluorescence quenching, which limits the application of anthracene derivatives in photonics. However, appropriate molecular design and pressure modulation can effectively regulate the luminescent properties of anthracene-based materials. Consequently, we successfully synthesized CZANP crystals that exhibit long-range, herringbone-like stacking arrangements of anthracene molecules, utilizing carbazole as a rigid steric hindrance substituent. The emission intensity of CZANP exhibits a significant increase within the pressure range of 1 atm to 1.0 GPa. Intermolecular C–H⋯π interactions between the carbazole and anthracene groups suppress the vibration and rotation of each corresponding group, thereby reducing non-radiative transitions. This accounts for the pressure-induced emission enhancement. The observed emission enhancement under low pressure conditions holds significant promise for advancing the potential of CZANP in optoelectronic applications.