Journal of Materials Chemistry C最新文献

Surface-enhanced Raman spectroscopy (SERS) depends on the development of a nanostructured substrate on which the excitation of a localized surface plasmon enhances the Raman scattering signals. Herein, we proposed a large-area three-dimensional (3D) pine needle with a dewdrop array (PNDA) nanostructure that can be easily fabricated via a film deposition technique with the help of a self-assembled polystyrene microsphere template and ultra-thin anodized aluminum oxide mask. Electromagnetic hotspots generated at the cracks or gaps between adjacent island structures of the PNDA are responsible for the SERS enhancement factor of 6.7 × 10⁶ when the structural parameters of the PNDA substrate are optimized. Experiments demonstrated that the rhodamine 6G (R6G) molecule can be probed with the PNDA substrate at the lowest concentration of 10⁻⁹ M using SERS. The homogeneity of the substrate was confirmed by verifying the relative standard deviation (RSD) of Raman spectra at different sites (6.5% at 611 cm⁻¹ and 8.3% at 1652 cm⁻¹). Moreover, crystal violet (CV) molecules were probed using our SERS experiment at the lowest detection concentration of 10⁻⁸ M. The results confirm that the PNDA structure is a reliable and sensitive SERS substrate to detect trace amounts of pollutants in an aquatic environment.

Yb_0.4Co₄Sb₁₂ compound is extensively studied for its superior thermoelectric properties, which are primarily attributed to the phonon-glass-electron-crystal (PGEC) approach upon Yb occupying the void-site in the unit cell. Herein, thermoelectric performances of co-doped Yb_0.4Co_3.96−xMo_xTi_0.04Sb₁₂ (x = 0, 0.02, 0.04, and 0.08) samples synthesized via a solid-state vacuum-encapsulated melt-quench-annealing method were measured in the temperature range of 300 K to 715 K. The framework of Mo⁴⁺ substituted at the Co²⁺/Co³⁺ site acted as a donor-like impurity, thereby significantly increasing the carrier concentration to 2.88 × 10²⁰ cm⁻³ for Yb_0.4Co_3.92Mo_0.04Ti_0.04Sb₁₂ at 300 K. Meanwhile, the electrical conductivity at 300 K approached a value of 756.73 S cm⁻¹ and further increased to 820 S cm⁻¹ at 711 K. The intensified point defect scattering from the dual doping strategy and enhanced grain boundary scattering simultaneously turned down the thermally active phonons to a suppressed κ_total of ∼2.11 W m⁻¹ K⁻¹ at 623 K, leading to an enhanced zT of ∼0.92 for Yb_0.4Co_3.92Mo_0.04Ti_0.04Sb₁₂, making it a promising candidate for intermediate temperature energy conversion applications.

Constructing p–n heterojunctions serves as a powerful strategy for boosting the generation and separation of photogenerated carriers, thereby promoting the photocatalytic production of hydrogen. This step is crucial for optimizing the performance of the photocatalytic hydrogen production. In the current research, a p–n type heterojunction photocatalyst, ZnCdS/CoMn₂O₄, with S-scheme heterojunction characteristics, was successfully synthesized. The optimized composite ZnCdS/CoMn₂O₄ demonstrated a 4.76-fold increase in hydrogen production compared to ZnCdS alone and exhibited excellent catalytic activity. Further characterization using techniques, like in situ XPS and DFT calculations, revealed that the p–n type heterojunction effectively promoted the separation of photogenerated electron–hole pairs, a key step for efficient hydrogen production. Furthermore, the enhanced redox capacity of the composite photocatalyst was confirmed by electron paramagnetic resonance analysis. The broadened light absorption range of the composite photocatalyst was also demonstrated, providing an ample number of active sites. This study offers insights into p–n photocatalysts with S-scheme heterojunction properties and proposes a promising approach for designing p–n heterojunctions to enhance photocatalytic hydrogen production.

Understanding the condensation process of two precursors in the Stöber process is crucial to enhance the complexity and applicability of silica hybrids. We present a simple and effective method to prepare functional silica hybrid particles with tunable properties through the co-condensation of tetraethoxysilane and an organoalkoxide precursor using a modified Stöber process. Three organoalkoxide precursors have been studied: (3-mercaptopropyl)triethoxysilane, (3-cyanopropyl)triethoxysilane, and (3-aminopropyl)triethoxysilane. All three investigated systems produce functional silica hybrid particles, as confirmed by various characterization techniques. Scanning transmission electron microscopy and nitrogen sorption analysis demonstrated that features such as the microstructure could be tailored by the careful selection of the second precursor. A drastic increase in the specific surface area can be obtained with 3cyanopropyltriethoxysilane: 270 m² g⁻¹ compared to 17 m² g⁻¹ in the unfunctionalized silica particles. Other important characteristics such as the degree of condensation and surface charge can also be influenced by precursor choice. The enhanced reactivity of 3-aminopropyltriethoxysilane yields a higher degree of particle functionalization. Nanoscale chemical mapping has been performed using energy-dispersive Xray spectroscopy and Auger spectroscopy. Homogeneous distribution of the functionalities within the hybrid particles occurs. The present work gives tools to easily tailor functional silica particles, thus providing simple ways to tune their properties to meet a wide range of applications.

In recent decades, optical thermometry has gained significant attention due to its promising properties, such as non-contact measurement, temperature mapping and immunity to electromagnetic interference. It overcomes the limitations of conventional temperature measurement methods and offers additional benefits. However, the widespread adoption of optical thermometry requires an expanded operating temperature range and improved sensitivity. Therefore, in this study, we focused on solid-solution sesquioxides, which are expected not only to enable the growth of single crystals with a cubic structure but also to allow for a wider selection of luminescence centers. We evaluated the applicability of (Lu, Y, Sc)₂O₃ single crystals doped with Pr³⁺ and Tb³⁺, which exhibit different temperature dependent behaviors, for optical thermometry. The optical temperature sensing properties evaluated using the fluorescence lifetime method revealed a maximal relative sensitivity of 1.53% K⁻¹ in the temperature range of 78–790 K for Pr³⁺, Tb³⁺:(Lu, Y, Sc)₂O₃. These results suggest that (Lu, Y, Sc)₂O₃ co-doped with Pr³⁺ and Tb³⁺ is a promising candidate for optical thermometry.

Liquid polarity plays an important role in healthcare, cell biology, molecular biology, drug delivery, and cell culture applications, and therefore the development of polarity-sensing sensors is of great importance. Here, a novel pyrene-bonded cove-type graphene nanoribbon (cGNRs-Pyrene) sensor has successfully been developed for liquid polarity sensing. An electron transfer complex (CTC) would be built when the cGNRs-Pyrene sensor was dispersed in the N-methyl-2-pyrrolidone (NMP) solution, while π–π stacking at higher concentrations induces aggregation-caused quenching (ACQ) and a decrease in fluorescence intensity. In addition, the cGNRs-Pyrene sensor exhibits an intramolecular charge transfer (ICT) effect, with its fluorescence intensity varying in different polar environments due to changes in the torsion angle between the pyrene groups and the core structure, making it suitable for liquid polarity sensing. In the THF–H₂O system, the fluorescence intensity of the cGNRs-Pyrene sensor exhibited a linear correlation with the polarity ratio (5–80%H₂O, R² = 0.9794). This sensor was used to monitor lipid droplet (LD) polarity in oleic acid-treated cells, sensitively detecting LDs' polarity changes, demonstrating significant potential for liquid polarity sensing in healthcare applications.

Sb-based metal halides have been a research focus because of their excellent optical properties. Pyramid-like [SbCl₅] polyhedra are the most distinct crystallographic feature. We analyzed 56 luminescent Sb-based hybrids from a list of 120 Sb chlorides by finding the corresponding best fitted ideal polyhedron. The results show a significant correlation between the distortion and photoluminescent quantum yield.

In co-host sensitized fluorescent devices, the triplet energy loss caused by a conventional fluorescent dopant (CFD) in the emitting layer (EML) prevents further improvement in device efficiency performance. In this article, we fabricate a thermally activated delayed fluorescence-sensitized fluorescent (TSF) organic light-emitting diode (OLED) with a dual-layer EML, which consists of an interface sensitized layer (ISL) and a red fluorescent EML. This device achieves a separation effect between the exciton generation region and the energy utilization region, which can effectively reduce the triplet energy lost through a CFD (DCJTB). Energy is mainly transferred from the sensitizer to the CFD through Förster energy transfer (FET). Furthermore, we introduce a TADF material (DMAC-MPM) into the ISL to form three RISC channels, corresponding to DMAC-MPM, DMAC-MPM:PO-T2T and TCTA:PO-T2T. The multiple reverse intersystem crossing (RISC) channels can effectively improve the up-conversion rate of triplet excitons, while also reducing exciton quenching in the ISL. After optimizing the relative position and thickness of the sensitizer (DMAC-MPM:PO-T2T) and the CFD, we achieve the maximum EQE of 14.33% in TSF-OLED device C1, which is the highest efficiency achieved among those of the reported fluorescent devices using DCJTB. The efficiency roll-off performance has also been improved, reaching 12.20% at a luminance of 1000 cd m⁻².

Delayed fluorescence pathways are a proven method to achieve significant efficiency gains in a myriad of technologies such as light-emitting diodes, multi-resonance effects leading to superirradiance or hyperafterglow/hyperfluorescence, and molecular logic. Scalability and the lack of low-cost materials hinder the search for optimised materials due to both time and financial constraints. A theoretical toolkit which could predict the properties of unknown materials could overcome this limitation. In this proof-of-concept work, we highlight a robust methodology which can predict the properties of an albeit unknown material with a high degree of efficacy with respect to experimental measurements. We first model the photophysical exciton dynamics of bay-site oxygen-fused quinolino[3,2,1-de]acridine-5,9-dione (OQAO) in the monomer-phase using density functional theory as a case study; an existing pathway of thermally activated delayed fluorescence (TADF) remains highly inefficient; an exciton has a 0.18% probability of undergoing a cycle of TADF. A reevaluation using a simplified dimer, where OQAO is paired with a resonant-emitter perylene, highlights that charge-transfer and multi-exciton phenomena are nearly non-existent. Paired homodimers were found to increase the efficiency by more than 70-fold. The kinetics for both monomer and dimer systems were then exported to an in-house Monte Carlo sampling codebase; while the monomer displayed minimal delayed fluorescence, the dimer was vital in capturing it. Evidence also suggested that exciton hopping plays an important role in the TADF process. This first-of-its-kind comprehensive study serves as a stepping stone highlighting that robust modelling of TADF systems is achievable.

The low open-circuit voltage (V_OC) imposed by the large energy loss, especially non-radiative recombination energy loss (ΔE_nr), accounts for the behindhand power conversion efficiency (PCE) of organic solar cells (OSCs), compared to those of silicon/perovskite solar cells. Hence, it is vital to reduce ΔE_nr to remedy the gap and further improve the PCEs. Herein, two terpolymer donors, DQ20 and DQ40, are developed via introducing a dimethyl dithieno[3,2-f:2′,3′-h]quinoxaline-2,3-dicarboxylate unit (TQC) into the backbone of D18 in consideration of the features of TQC. The introduction of TQC endows DQ20 and DQ40 with down-shifted energy levels and improved miscibility with the electron acceptor, L8-BO. As a result, the V_OC increases from D18:L8-BO (0.895 V) to DQ20:L8-BO (0.906 V) to DQ40:L8-BO (0.920 V)-based OSCs, mainly ascribed to the gradually decreased ΔE_nr. Moreover, the DQ20:L8-BO blend film exhibits fine phase separation with ordered molecular stacking, and thus achieves the highest charge carrier mobility and weakest charge recombination in devices for the best J_SC (27.11 mA cm⁻²) and FF (78.73%). Consequently, DQ20:L8-BO based OSCs afford a higher PCE of 19.35%, compared with D18:L8-BO and DQ40:L8-BO counterparts. This work demonstrates that ternary copolymerization is an effective strategy to realize suppressed ΔE_nr and high efficiency via finely tuning the energy level offset and miscibility between the donor and acceptor.