Journal of Materials Chemistry C最新文献

Understanding the charge behavior inside organic layer interfaces in multilayer organic light-emitting diodes (OLEDs) is essential for improving device efficiency and lifetime. However, examining charge transport during voltage application passing through these organic interfaces in ultrathin and in encapsulated OLEDs is extremely challenging. To address this, electronic sum-frequency generation (ESFG) spectroscopy, a non-invasive technique, offers interface-selective information on the electronic structure of organic interfaces under light-emitting conditions. This study demonstrates the capabilities of ESFG spectroscopy by comparing the spectra of three different OLED devices with buried interfacial electronic structures under operation. The ESFG spectra revealed ESFG signal increases in intensity at the absorption band of the hole transport material upon voltage application and decreases in ESFG intensity at the absorption band of the light emitting layer. This observation is attributed to the electrical potential balance of the specific organic layers inside the devices caused by charge injection into the devices. Time-resolved ESFG measurements using square-wave pulse voltages have also enabled a detailed investigation of the electric field formation process caused by charge injection into the devices. This technique is an innovative, highly effective, and nondestructive spectroscopic approach for investigating electric-field formation owing to injected charges in solid-state thin-film devices.

MAPbI₃ single crystals possess excellent semiconductor properties and exhibit broad prospects in applications such as photodetection and photovoltaics; however, it is a big challenge to achieve macroscopic piezoelectricity. Herein, MAPbI₃ semiconducting single crystals were fully polarized with a series of pulsed electric fields, and their macroscopic piezoelectric coefficient (d₃₃) value was ∼8.3 pC N⁻¹. A multifunctional force-light detector was prepared using the MAPbI₃ piezoelectric semiconductor. Initially, the self-powered photodetector could detect a 405 nm wavelength laser with an energy density of ≥4 nW cm⁻². Without applied pressure, the self-powered photodetector exhibited a high responsivity of ∼129.6 A W⁻¹ and a high detectivity of ∼7.1 × 10¹⁴ jones. Additionally, external force could optimize the performance of the photodetector, increasing its responsivity and detectivity by 25% under a pressure of 1.5 N and laser illumination intensity of 4.15 mW cm⁻². This work demonstrates that the MAPbI₃ piezoelectric semiconductor is promising in the development of a multifunctional light-force-electrical coupling device.

Humidity monitoring is ubiquitously used in industries like robotics, human–machine interfaces, and electronic skins, where humidity sensors ensure device protection and data-gathering accuracy. Therefore, this work focuses on developing sustainable, flexible, and highly sensitive cellulose-based humidity sensors. To achieve this goal, a Taguchi design of experiments was suggested to optimize four key ink formulation parameters: carbon black (CB) fillers, cellulose nanofibers (CNF), polyvinyl pyrrolidone (PVP) binders, and glycerol plasticizers. The resulting formulations were subjected to material, electrical resistance, adhesion, water contact angle, and hygroresistive characterization. The results detail how the factors of interest influence the electrical response of the sensors, their sensitivity, and ink adhesion to the substrate. Moreover, increasing the CNF, glycerol, and PVP while reducing CB enhances sensitivity and ink performance. Optimized sensors demonstrated high responsiveness between 20% and 90% relative humidity, with an exponential growth rate of 9.6–10.0% RH⁻¹. The optimized sensors were also assessed regarding their repeatability across 10 cycles, stability to bending, and insensitivity to temperature variation. These findings highlight the role of formulation interactions in sensor performance and demonstrate the potential of eco-friendly and highly sensitive humidity sensors for next-generation flexible electronics.

Chiral hybrid metal halides have attracted much attention in optoelectronic fields such as encryption storage, security monitoring, and three-dimensional (3D) displays, due to their low cost, low toxicity, good stability, high luminescence efficiency, tunable emission, and chiroptical and nonlinear optical properties. Here, a pair of chiral manganese(II)-based hybrid chloride single crystals (R/S-2-mpip)MnCl₄·2H₂O and (rac-2-mpip)MnCl₄·2H₂O (mpip = methylpiperazinium) were synthesized by a slow evaporation method. The crystal structures, X-ray photoelectron spectroscopy (XPS), second harmonic generation, band gap calculation and photoluminescence (PL) were systematically studied. (R/S-2-mpip)MnCl₄·2H₂O and (rac-2-mpip)MnCl₄·2H₂O single crystals exhibited strong red emission characteristics caused by d–d transition of free Mn²⁺ when heated to 383 K. Moreover, heated (R/S-2-mpip)MnCl₄·2H₂O materials exhibit the obvious circular dichroism and red circularly polarized luminescence characteristics with a moderate luminescence dissymmetry factor g_lum value reaching ±1.2 × 10⁻³, which provides a new research direction for further applications from anticounterfeiting to 3D displays, as well as encryption storage.

Aramid paper materials, renowned for their exceptional mechanical properties, insulting capabilities, and thermal stability, are crucial for next-generation electrical and electronic devices. Among them, the poly(m-phenylene isophthalamide) (PMIA) paper exhibits practical potential through its simple and cost-effective preparation methods. However, the traditional PMIA paper produced by the wet-laid process suffers from interfacial defects, while the PMIA nanopaper prepared via protonation is more homogeneous, yet lacks the crystalline structure to sustain high mechanical strength. Here, PMIA is blended with a heterocyclic aramid (HA), a derivative of aramid, to prepare co-blending paper. The HA contains benzimidazole groups in its molecular structure, providing more hydrogen bond-forming sites that enhance the mechanical robustness. The strengthened hydrogen bonding network facilitates a stronger interaction between PMIA and HA, as well as a reduced interchain spacing, which tailors the chain packing structure with a smaller free volume fraction, conducive to a higher breakdown strength. Additionally, the HA and PMIA share a common solvent for co-blending, highly simplifying the preparation process. At an optimized HA content of 20 wt%, the PMIA/HA co-blending paper exhibits high structural integrity, characterized by a dense and compact configuration. Its Young's modulus is 4.6 GPa and breakdown strength is 300.6 kV mm⁻¹. Moreover, hydrogen bonds effectively suppress dielectric loss. Due to its superior flexibility, colorability, and flame retardancy, the aramid co-blending paper exhibits versatile and high-performance features for a wide range of applications.

While physical reservoir computing offers a promising approach for efficient information processing, identifying suitable substrates remains challenging. Here, we demonstrated that colloidal albumen proteins could function as an effective physical reservoir for classifying multivariate datasets and electrocardiogram (ECG) signals. We exploited the nonlinear dynamics of protein macromolecules and ions in the albumen to perform high-dimensional mappings of input data. Our albumen-based reservoir achieved classification accuracy comparable to conventional machine learning methods on benchmark datasets while consuming over 5000 times less energy during training. Notably, the reservoir exhibited short-term plasticity analogous to biological synapses, with conductance spikes and fading memory. This bio-inspired computing paradigm not only offered a sustainable alternative to traditional architectures but also provided insights into the information-processing capabilities of biological systems. Our findings opened new avenues for low-power, environmentally friendly computing solutions with potential applications in real-time health monitoring and edge computing.

Full-spectrum laser-driven white lighting shows promise for high-luminance solid-state illumination and is highly desirable for lighting application domains such as education, healthcare, and residential lighting. However, obtaining both a high color rendering index (Ra) and high luminous efficiency (LE) concurrently poses a great challenge for the development of laser-driven white lighting. Herein, a novel tricolor phosphor-in-glass film (PiGF) is designed and fabricated via a facile low-temperature co-sintering strategy. ZnO–Li₂O–SiO₂ (ZLS) glass along with Y₃Al₅O₁₂:Ce³⁺ (YAG), CaAlSiN₃:Eu²⁺ (CASN), and Lu₃(Al, Ga)₅O₁₂:Ce³⁺ (LuAGG) phosphors was coated onto sapphire substrates via the blade-coating method and then subjected to low-temperature co-firing, fabricating composite phosphor-in-glass film (PiGF) samples for full-spectrum laser-driven white lighting. High LE and Ra were achieved by optimizing the glass layer thickness, phosphor concentrations, phosphor ratio, film structure, and sintering process. The YAG-PiGF achieves a high luminous flux (LF) of 1129 lm and a Ra of 62. Further addition of CASN and LuAGG phosphors fills the color gaps, resulting in a composite PiGF with a high Ra of 92 and a LE of 212 lm W⁻¹. The excellent balance between Ra and LE makes this color converter highly promising for high-quality laser lighting applications.

The lead-free Cs₃Bi₂Br₉ perovskite has emerged as a promising candidate for memristor and artificial synapse devices due to its high environmental stability and low toxicity compared to lead-based alternatives. In this work, we successfully prepared a high-quality Cs₃Bi₂Br₉ perovskite film via a simple spin-coating method combined with low-pressure assisted treatment. Based on the obtained Cs₃Bi₂Br₉ film, a memristor with the structure of W/Cs₃Bi₂Br₉/ITO was fabricated. The memristor demonstrated excellent resistive switching performance, including analog-switching behavior, high environmental stability (>11 months), low operating voltages (V_FORMING ∼ 0.65 V, V_SET ∼ 0.53 ± 0.08 V, and V_RESET ∼ −0.83 ± 0.11 V), fast switching speed (<1 μs), and long switching endurance (>1100 cycles). Furthermore, the synaptic plasticity aspects such as short-term plasticity, long-term plasticity, and synaptic weight potentiation and depression were successfully simulated via pulse-train measurement. Finally, a fully connected neural network built using the W/Cs₃Bi₂Br₉/ITO memristor can obtain an accuracy of about 90% in recognizing handwritten digits. The results indicate that the lead-free Cs₃Bi₂Br₉-based memristor has great potential in high-stability, cost-effective, eco-friendly, and low-power consumption nonvolatile memory and neuromorphic computing applications.

The study of the mechanoluminescence enhancement (MLE) mechanism has been a challenging topic in the field of luminescent materials. Here, we implanted organoboron units with a steric hindrance effect into the molecular backbone and achieved the synthesis of MLE molecules using molecular engineering and crystal engineering. ortho-, meta-, and para-substituted organoboron compounds, namely o-NAB, m-NAB, and p-NAB, were synthesized, where o-NAB showed notable MLE, whereas m-NAB and p-NAB showed decreased fluorescence intensity upon mechanical activation without the assistance of solvent. Our study finds that the steric conformation resulting from different substitution positions plays a decisive role in the fluorescence performance. Grinding releases spatial stress in the o-NAB structure, thereby affecting the process of mechanoresponsive fluorescence transition. Our research provides a congested position strategy for constructing MLE molecules, which not only enhances the fundamental understanding of MLE mechanisms but also bears significant implications for future research.

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) have been widely used in plant cultivation. However, exploring NIR phosphors with specific wavelengths and high efficiency is still the main task. In this paper, a NIR phosphor, Lu₃Ga_5−2xMg_xGe_xO₁₂ (LGMG):0.05Cr³⁺, with an emission center wavelength of 726 nm was investigated. After employing the co-substitution strategy, it was found that the strength of the crystal field in the vicinity of Cr³⁺ gradually weakened, resulting in broadening of the emission spectrum to the full width at half maximum (FWHM) of 155 nm. Notably, the developed phosphors have high IQE values and relatively better thermal stability. After optimization, the absorption spectrum of the obtained broadband near-infrared luminescent phosphor showed a high degree of matching with the absorption spectrum of the phytochrome P_FR. NIR pc-LEDs devices were successfully prepared by combining the LGMG:Cr³⁺ phosphor with commercialized blue LED chips. This phosphor has potential applications in plant lighting to promote plant growth.