Journal of Materials Chemistry C最新文献

Plasmonic materials, such as gold nanoparticles (AuNPs), exhibit significant extinction and near-field enhancement across the visible and near-infrared spectrum, attributable to localized surface plasmon resonances (LSPRs). Epsilon-near-zero (ENZ) materials, such as aluminium doped zinc oxide (AZO) are known in non-linear optics for their ability to generate and manipulate light-matter interactions through processes like higher harmonic generation. Combining doped ZnO with plasmonic materials therefore holds promise for enhancing non-linear efficiencies and tuning their operational wavelengths. To date, however, only top-down structures based on plasmonically decorated thin ENZ films have been realized, and no colloidal and scalable route to obtain these hybrid materials has been reported yet. Here, we introduce a novel colloidal synthesis approach for fabricating Au@AZO core@shell nanoparticles with tunable core size, shell thickness, and dopant concentration, allowing for the spectral alignment of the LSPRs of the AuNPs with the non-linear optical properties of the AZO shells. Our method involves the colloidal synthesis of gold cores followed by an ascorbic acid-assisted process to deposit polycristalline ZnO and AZO shells, resulting in core diameters ranging from 25 to 69 nm, shell thicknesses from 16 to 47 nm, and aluminium doping levels between 0 and 4 at%. Our procedure widens the range of hybrid plasmonic nanostructures that can be colloidally synthesised, opening new possibilities for the large scale fabrication of high-performance nanomaterials for integration in photonic, photocatalytic, and sensing applications.

Conducting polymers are important for areas including energy storage, displays, sensors, nanooptics, and bioelectronics. Vapor phase polymerization (VPP) of conducting polymers can provide highly conductive homogenous thin films but was so far reported only for a limited number of materials. Here, we report VPP deposition of the low bandgap conducting polymer poly(thieno[3,4-b]thiophene):tosylate (pT34bT:Tos) and propose an application for dynamic structural coloration. Optimized films show high electrical conductivity of around 750 S cm⁻¹, manifested optically as wide infrared absorption extending beyond 2000 nm. Electrochemical reduction reveals a neutral low bandgap peak around 1030 nm, making pT34bT comparably transparent also in its neutral state as opposed to other common conducting polymers. Moreover, the VPP process allows to spatially control the polymer properties and thickness via a UV exposure step before polymerization. We exploit this technique to create structurally colored images using the polymer as cavity spacer layer, locally varying its thickness and optical properties. We finally demonstrate dynamic tunability of structural colors based on the application of different potentials in an electrochemical cell.

Ag₈SnS₆ (ATS) nanoparticles, with a band gap of 1.35 eV, which is located exactly at the Schockley–Queisser optimal value for a single-junction solar cell, were utilized as a photoabsorber component in solid state photovoltaic devices. The as-made particles were capped with long aliphatic chains of oleic acid and oleylamine. After surface functionalization of the shorter and extremely basic formamidinium cations, an increase of the absorption coefficient throughout the visible spectrum range was observed. The ligand exchange led also to a slight increase of the band gap, by a value of 0.05 eV. XRD, XPS, UPS, diffuse reflectance, TEM and EDX characterization studies revealed the structure of the nanoparticles and finally proof-of-concept thin film solar cells were fabricated. A maximum photoconversion efficiency of 0.22% was achieved for the as-made particles.

Conjugated polymers with simple chemical structures are essential for the commercialization of organic solar cells (OSCs). However, a simplicity-performance dilemma arises, as current design principles often result in an inverse correlation between these two factors, significantly hindering the commercialization of OSCs. In this study, we investigated the impact of fluorine substitution positions on benzene rings within polythiophenes (PTs), leading to two polymers composed of non-fused rings of o-difluorobenzene-quarterthiophene and p-difluorobenzene-quarterthiophene, namely, Po2F and Pp2F. The Po2F/Y6BO devices achieved a remarkable efficiency of 15.45%, with the active layer fabricated via layer-by-layer (LBL) spin coating, significantly surpassing the Pp2F/Y6BO blend (12.14%) and ranking among the top-performing oligothiophene-based OSCs. The enhancement is mainly attributed to improved phase separation, reduced exciton lifetimes, and suppressed mixing compatibility with Y6BO of Po2F, compared to Pp2F. In addition, the simple polymer Po2F demonstrated a much higher figure of merit (FOM) in chemical accessibility than polymers with fused rings, indicating its great potential for cost reduction. Beyond its role as a donor, Po2F also enhanced the efficiency of PM6:L8BO from 17.74% to 19.05% and extended T₈₀ from 239 to 377 hours when used as an interlayer between the PEDOT:PSS buffer layer and the active layer. This study highlights the significance of a polymer donor-based non-fused ring towards commercially viable OSCs and offers valuable insights for designing high-performance polymers.

Photonic glass materials have drawn significant attention in emerging applications owing to their unique structural features with pseudo isotropic photonic bandgaps, short-range order and angular-independent coloration. In this review, we systematically summarize a variety of common fabrication strategies based on colloidal nanoparticles for photonic glasses and their promising applications. In particular, inverse photonic glassy pigments are discussed for improving saturation and purity of quasi-crystalline structural colors. Additionally, the role of inorganic semiconductor particles with a high refractive index upon increasing the dielectric constant for producing non-iridescent photonic materials is described. Finally, this review analyses the critical challenges and highlights the promising new areas of photonic glass materials for future applications.

Ceramics composed of Zn_0.7Mg_0.3TiO₃ are employed in creating microwave devices because of their outstanding dielectric characteristics. Nonetheless, their elevated sintering temperature poses a significant challenge, rendering them unsuitable for meeting industrial production standards. Innovative Zn_0.7Mg_0.3TiO₃ ceramics, enhanced with V₂O₅ and TiO₂, were synthesized using a solid-state reaction technique. Findings revealed that V₂O₅ and TiO₂ serve as effective sintering aids, leading to an improved densification rate and a decrease in the sintering temperature. Exceptional microwave dielectric characteristics were achieved by sintering Zn_0.7Mg_0.3TiO₃ ceramics (x = 1.5) at 950 °C: ε_r ≈ 20.92, Q × f ≈ 25862.7 GHz (@8.6 GHz), and τ_f ≈ −15.2 ppm °C⁻¹. Additionally, the optimal τ_f value is nearly 30% higher than that reported in existing literature (which is only −55 ppm °C⁻¹). Based on the P–V–L theory, Zn/Mg–O and Ti–O bonds contribute significantly to the dielectric constant and internal losses. The τ_f parameter is influenced directly by the distortion within the octahedral [TiO₆]. Incorporating V₂O₅ and TiO₂ into Zn_0.7Mg_0.3TiO₃ ceramics endows them with considerable potential for utilization in LTCC microwave devices.

One-dimensional (1D) antiferromagnetic chains are fascinating because of their exotic quantum phenomena. However, isolating large-spin S chains remains challenging as even minimal interchain interaction J′ tends to drive unwanted long-range ordering. Here, we report on the synthesis, crystal structure, magnetism, optical, and electronic properties of two isostructural metal–organic frameworks (MOFs), [M₂(mCB-L)₂(μ₂-H₂O)₂(DMF)₄]_n·solv (M = Co(II) (mCB-Co) or Ni(II) (mCB-Ni)), which feature water-bridged Co (S = 3/2) or Ni (S = 1) spin chains that are effectively separated by bulky carborane linkers (1,7-di(4-carboxyphenyl)-1,7-dicarba-closo-dodecaborane, mCBLH₂). The temperature-dependent susceptibility reveals strong antiferromagnetic interactions with significant intrachain coupling, J_Co/k_B = −4.65 K (mCB-Co) and J_Ni/k_B = −23.36 K (mCB-Ni), yet confirm the absence of long-range order down to 0.3 K due to negligible interchain interactions, as corroborated by specific heat data. This indicates extremely small J′, with J′/J < 4.7 × 10⁻⁴ (3.7 × 10⁻⁵) for Co (Ni) MOFs, making these new materials nearly ideal 1D antiferromagnets. Additionally, optical band gaps were estimated via the Kubelka–Munk method, yielding an increase from 3.83 eV for mCB-Co to 4.20 eV for mCB-Ni, showcasing tunable electronic properties across the two MOFs.

The quasi-bound states in the continuum (quasi-BIC) are uniquely attractive in the fields of nonlinear modulators, optical switches, and sensing due to their ultra-high radiative quality factor. The implementation of quasi-BIC on metamaterials can trap the energy of the electromagnetic wave whose wavelength is larger than the diffraction limit in the metamaterial without radiation leakage, leading to the development of highly sensitive terahertz (THz) biosensors. In this paper, we manipulate the interferometric coupling between multipoles by breaking the symmetry of the metal structure on the metamaterial to excite high-quality quasi-BIC resonances. In addition, we experimentally integrated colloidal gold on the proposed quasi-BIC metamaterial and combined it with microfluidics technology, in which the tip effect of colloidal gold enhances the light–substance interactions and thus improves the detection of the sensor, and realized the micro-liquid detection of imidacloprid solution with a detection limit of 1 ng mL⁻¹. We then used the continuous wavelet transform instead of the traditional Fourier transform and created a two-dimensional wavelet coefficient card that provides a more accurate method for determining solution concentration. This novel sensing platform offers the possibility to reduce the interference of water on THz signals and achieve highly sensitive detection of trace liquids via THz metamaterials, and this pioneering approach opens up a new avenue for liquid-based THz biosensing.

Perovskite nanocrystals (NCs) exhibit remarkable potential for light-emitting applications due to their solution processability, high photoluminescence quantum yield (PLQY), and tunable bandgaps. However, surface defects on NCs and the insulating nature of the surrounding long-chain ligands often impede the performance of the resulting perovskite light-emitting diodes (PeLEDs). Innovative strategies to address these challenges are crucial for advancing the environmental stability of perovskite NCs and high-efficiency PeLEDs. In this study, red light-emitting CsPbBr_xI_3−x NCs were synthesized via the hot-injection method, employing diphenylammonium iodide (DPAI) and diphenylammonium bromide (DPABr) as surface passivating ligands. These ligands not only compensated for surface defects of NCs through released I⁻ and Br⁻ anions but also improved charge carrier injection by π-conjugated benzene rings. Consequently, the PLQY was improved from 55% of the pristine NCs to 80% and 78% for those passivated with DPAI and DPABr ligands, respectively. The environmental stability and thermal stability of perovskite NCs were also enhanced under ambient conditions. The optimized red PeLED with the DPAI-modified perovskite NCs showed 2.8-fold higher luminance and 3.5-fold higher current efficiency than the control device. Similarly, the device based on the DPABr-modified NCs also exhibited significant improvements, showcasing the potential of surface ligand engineering with diphenylammonium halides in advancing PeLED performance.

The success of the photoalignment of liquid crystals provides displays and other optical applications with more possibilities, compared with the surface rubbing technique. Especially, it is highly required for applications requiring liquid crystal alignment on curved surfaces, for which surface rubbing is hard to apply. Photodimerization of photoactive species coated on the substrate under linearly polarized light irradiation is one of the photoalignment methods. In this work, we present a study on the photoalignment behaviors of a novel low-molecular-weight, H-bond donor, acceptor, and coumarin-containing compound that can be spray-coated on curved surfaces. The photoalignment of liquid crystals using this coumarin-containing compound is investigated by monitoring the polarized absorption of a dichroic dye-doped nematic liquid crystal. It is found that the order parameter can reach about 0.5 by adjusting the thickness of the spray-coated layer and the polarized light intensity. In addition to liquid crystal alignment on a curved surface, the reversible photoreaction of coumarin is explored to reprogram the photoalignment layer to achieve control in either the degree or direction of the liquid crystal alignment. The results show that the novel structure of the coumarin-containing compound is promising for photoalignment of liquid crystals.