Journal of Materials Chemistry C最新文献

In recent years, hybrid metal halides have gained considerable attention for optoelectronic applications due to their outstanding photophysical properties, despite challenges with stability. In this study, we present the design and synthesis of a highly stable and efficient zero-dimensional (0D) hybrid copper(I) halide, [FBZPA]₄Cu₅Br₁₃ (FBZPA = protonated 1-(4-fluorobenzyl)piperazine)), for advanced scintillation and solid-state lighting applications. This material exhibits efficient yellow light emission with a photoluminescence quantum yield of 88.5%, driven by radiative recombination of self-trapped excitons, which is facilitated by structural deformation and strong electron–phonon coupling within the 0D structure. [FBZPA]₄Cu₅Br₁₃ shows excellent scintillation properties, including a high light yield (∼39 100 photons MeV⁻¹), a low detection limit (0.102 μGy_air s⁻¹), and a high spatial resolution (15 lp mm⁻¹), making it an ideal candidate for high quality X-ray imaging. Additionally, we fabricated a white light-emitting diode (WLED) by combining [FBZPA]₄Cu₅Br₁₃ with a commercial blue phosphor on a UV chip. The WLED exhibited a high color rendering index of 90 with stable emission. It demonstrates remarkable stability, retaining its structure and optical properties after exposure to water, and intense light, without requiring encapsulation or chemical modifications. This study highlights [FBZPA]₄Cu₅Br₁₃ as a promising material for next-generation scintillation and solid-state lighting applications.

In this study, an atypical copper oxynitride (Cu_xO_yN_z) system was synthesized with tunable Cu–O–N compositions. Structural analyses using X-ray diffraction, Rietveld refinement, micro-Raman, and high-resolution transmission electron microscopy confirmed the presence of Cu–O, Cu–N, and metallic Cu phases in the Cu_xO_yN_z system. Physicochemical investigations revealed the distinct properties of O_rich-, N_rich-, and Cu_rich–Cu_xO_yN_z systems. The O_rich–Cu_xO_yN_z system exhibited enhanced stability in photocatalytic reactions, while the N_rich–Cu_xO_yN_z system displayed a broader optical response due to a lower bandgap energy compared to pure-CuO. The Cu_rich–Cu_xO_yN_z system, with its meta-stable Cu–N lattice, formed a plasmonic ohmic junction, facilitating efficient charge transfer and leading to enhanced photocatalytic activities. The photocatalytic dye degradation (in %), H₂ evolution (in μmol g⁻¹ h⁻¹), and NH₃ formation (in μmol g⁻¹ h⁻¹) over the O_rich–Cu_xO_yN_z system (∼95/963.6/495.8) were found to be superior compared to those over the N_rich–Cu_xO_yN_z (∼73/741.8/435.4) and bare oxide (∼62/418.3/270.2) systems. Unlike conventional bare or N-doped copper oxide materials, the synthesized copper oxynitride systems demonstrated synergistic properties, showing organized interactions among oxide, nitride, and metallic components. This research paves the way for a better understanding of the formation mechanism of atypical unary metal oxynitride systems and highlights their unique features as an emerging class of materials for energy and environmental applications.

The direct conversion of heat and electric energy through thermoelectric effects is one of the effective ways to improve energy efficiency and reduce carbon emissions. Thermoelectric parameters are the basis to evaluate the thermoelectric conversion efficiency of thermoelectric materials. Accurate and rapid characterization of thermoelectric parameters is the foundation and key of the optimization design and application of thermoelectric materials. Small-scale and micro-nanostructure of materials can not only effectively change their thermal conductivity but also affect their electrical conductivity and Seebeck coefficient, thus significantly improving thermoelectric conversion efficiency. Note that the thermal rectification effect caused by structural regulation can effectively change thermal conductivity, further affecting thermoelectric performance. Therefore, it is urgent to study the coupling mechanism between micro-/nano-scale structural regulation and thermoelectric properties. In this work, an in situ characterization technique is used to study the integration of structural regulation and thermoelectric properties of micro-/nanomaterials, and the coupling mechanism is experimentally investigated. The relation between thermoelectric properties and thermal rectification caused by structural regulation is also discovered. Results demonstrated that structural regulation could effectively improve the ZT value with a maximum improvement of nearly 1.7 times and further to 2.4 times because of the thermal rectification effect, which indicates that micro-nanostructural regulation is an effective approach to improve thermoelectric performance.

Colloidal lithography offers a cost-effective and straightforward method for fabricating periodic arrays, utilizing colloidal spheres as microlenses to create patterns in a photoresist. However, the exposure depth remains a challenge. By utilizing PDMS to fill colloidal films, high-aspect-ratio photoresist nanopillars were employed as the structural basis for the successful fabrication of both metallic resonant type and non-metallic anti-reflective type broadband near-perfect optical absorbers. According to simulated light beams and the resulting photoresist patterns, the introduction of PDMS not only made the colloidal mask flexible and reusable, but also significantly increased the beam convergence depth, enabling the formation of high-aspect-ratio photoresist patterns. In simulations, the effective focused beam depth was sensitive to the film's refractive index, colloidal diameters, and ratios of the sphere diameter to periodicity of colloidal arrays, resulting in a depth of 2828 nm under optimal parameters. In experiments, photoresist arrays with pillar heights reaching up to 3374 nm and the corresponding depth-to-width ratio of 5.04 were achieved. Additional petal-shaped or octopus-shaped pillars were also created during PDMS-assisted lithography. A metallic absorber, based on the conformal Pt coating, achieved an average absorbance of up to 98.3% over the range from 400 nm to 1100 nm, with a minimum absorptivity of 96%. An all-dielectric optical absorber, employing photoresist nanopillars for impedance matching, exhibited an average absorptivity of 92.4% within the same wavelength range.

With the successful fabrication of two-dimensional (2D) magnets and ferroelectrics, constructing multiferroic van der Waals (vdW) heterostructures offers a practicable route toward high-performance nanoelectronics and spintronics device technology. In this work, based on first-principles calculations, we propose a Mn₂ClF/Sc₂CO₂ vdW multiferroic heterostructure by stacking the A-type antiferromagnetic (AFM) material Mn₂ClF and the 2D ferroelectric material Sc₂CO₂. Our findings demonstrate that the AFM layer Mn₂ClF will transition between semiconductor and half-metal by reversing the ferroelectric polarization state of the Sc₂CO₂ layer. This transition is attributable to the different band alignments of Mn₂ClF and Sc₂CO₂ for different polarization states. Then, we design a multiferroic tunnel junction (MFTJ) based on the Sc₂CO₂/Mn₂ClF/Sc₂CO₂ vdW multiferroic heterostructure, which realizes the function of four-state information storage. Furthermore, we show that the spin polarization of near 100% is achieved by applying a small bias on the MFTJ. These results present a promising avenue for the application of multifunctional spintronic devices.

Copper(I) thiocyanate (CuSCN) is a unique wide band gap, p-type inorganic semiconductor with extensive opto/electronic applications. Being a coordination polymer, CuSCN requires processing by coordinating solvents, such as diethyl sulfide (DES). The strong interactions between CuSCN and DES lead to the formation of SCN⁻ vacancies (V_SCN), which are detrimental to hole transport. In this work, we rationally modify copper(I) thiocyanate (CuSCN) through the use of chemically compatible copper(I) halides (CuX, where X = Cl, Br, or I). On assessing the device characteristics of thin-film transistors employing CuX-modified CuSCN as the p-channel layer, adding 5% of CuBr is found to be the most optimal condition. The hole mobility is increased by 5-fold to 0.05 cm² V⁻¹ s⁻¹ while the on/off current ratio is also enhanced up to 4 × 10⁴. The drain current in the off-state does not increase whereas the trap state density is reduced, and the performance improvement can be attributed to the defect healing effect. Detailed characterization by synchrotron-based X-ray absorption spectroscopy reveals the recovery of the coordination environment around Cu, confirming that Cl⁻ and Br⁻ can effectively passivate V_SCN defects. In particular, CuBr further improves film uniformity and smoothness. The simple protocol based on common chemicals reported herein is applicable to the standard CuSCN processing recipe, which is currently applied across a wide range of electronic and optoelectronic devices.

Perovskite nanocrystals (NCs) offer exceptional optical properties but suffer from limited stability. Encapsulation with polymer materials is a promising approach to enhance their stability. However, traditional characterization techniques often fall short in providing a comprehensive understanding of the protection mechanism. We developed a high-throughput characterization platform based on nanoparticle arrays to investigate the protective effects of different polymers on CsPbBr₃ NCs. Using this platform, we found that polystyrene (PS) films, even at relatively thin thicknesses, significantly outperform thicker poly(methyl methacrylate) (PMMA) films in preserving NC photoluminescence. This suggests that the intrinsic properties of the polymer, beyond its thickness, play a crucial role in protecting NCs. Our findings provide valuable insights into the design and selection of effective polymer encapsulation materials for perovskite NCs.

Secondary electrons play a vital role in extreme ultraviolet lithography (EUV-L), as low-energy electrons (LEEs) induce the solubility switch of the photoresist via electron-induced reactions. However, optimizing EUV absorption at 92 eV and addressing the relatively long inelastic mean free path (IMFP) of LEEs, which can lead to pattern blurring, remain critical challenges. Here, first-principles calculations based on time-dependent density functional theory (TDDFT) are conducted to evaluate how chemical substitutions in metal and ligand sites affect both EUV absorption and the energy loss function (ELF) of LEEs in oxalate systems. Results highlight that atomic cross-sections alone are insufficient for optimizing photoabsorption, and electronic structure effects must be considered. Analysis of the ELF of LEEs reveals that iodine-containing systems exhibit a higher ELF at low energies, suggesting a reduced IMFP. Additionally, iodine incorporation shows potential to lower the band gap, which may further reduce the IMFP of LEEs in photoresists. These findings underscore the significance of electronic structure effects in EUV-L and demonstrate the value of first-principles calculations in optimizing photoabsorption and electron behavior for next-generation lithography applications.

Organic phototransistors (OPTs) built from organic single crystals offer distinct advantages over their thin-film counterparts due to their superior charge transport, large surface area, and defect-free molecular arrangement. However, the progress in developing high-performance n-type organic semiconductors has largged behind that of p-type materials, posing a challenge to the advancement of organicelectronic devices. To address this issue, we synthesized novel tetra-bromo-substituted chiral perylene diimides, which self-assembled into single crystals, offering potential of n-type semiconductors. Traditional doping techniques often risk damaging the delicate crystal structure; therefore, we implemented a mild surface doping method using aniline vapor, which preserves the structural integrity of the crystals while significantly enhancing their optoelectronic properties. The doped devices exhibited a remarkable improvement in charge transport, with electron mobility increasing four times to 1.19 × 10⁻² cm² V⁻¹ s⁻¹. Furthermore, the optoelectronic characteristics were significantly improved simultaneously, with the external quantum efficiency increasing over two-fold, and response times becoming notably faster. These enhancements are attributed to the increased charge carrier density and improved exciton separation efficiency following doping. This study demonstrates that our surface doping strategy is a highly effective approach for optimizing the performance of organic single-crystal OPTs, providing a promising pathway for future applications in advanced optoelectronic devices.

In this study, we successfully synthesized high-purity CsPbBr₃ perovskite nanocrystals (NCs) and nanowires (NWs) using a hot-injection method within an amine-rich environment, followed by a detailed analysis of their structural and optical properties. By carefully tuning the ratios of oleylamine (OAm) and octylamine (OctAm), as well as optimizing reaction temperature and time, we achieved enhanced morphology and photoluminescence characteristics of the products. The results indicate that increasing the amine content reduces the nanowire thickness and improves crystallinity, yielding NWs with an approximate diameter of 3 nm and NCs with a uniform size distribution of 9.7 ± 0.2 nm. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) confirmed that the CsPbBr₃ nanostructures exhibit a pure orthorhombic phase. Photoluminescence (PL) and UV-vis absorption analyses revealed narrow emission peaks at 520 nm and 465 nm for NCs and NWs, respectively, with the NWs showing a pronounced blue shift and a primary exciton absorption peak at 450 nm, indicating a strong quantum confinement effect. Time-resolved photoluminescence spectroscopy (TRPL) measurements showed an average exciton lifetime of 15.29 ns for NWs, which is notably longer than the 10.55 ns observed for NCs. Femtosecond transient absorption spectroscopy (fs-TA) further demonstrated significant differences in ground-state bleach (GSB) dynamics between the nanostructures, with NWs reaching peak bleach at 9.32 ps compared to 6.16 ps for NCs. These findings highlight the slower carrier recombination rate in NWs, which enhances quantum confinement effects. This work provides both theoretical and experimental insights into the potential application of one-dimensional perovskite nanostructures in high-efficiency optoelectronic devices.