Latest ArticlesLead-free hybrid double perovskites (LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic properties has not yet been investigated. Herein, we synthesized two new Ruddlesden–Popper LFHDPs, namely (C5H12N)4AgBiI8 (CAB-1) and (C6H14N)4AgBiI8 (CAB-2) using cyclopentylamine and cyclohexylamine as monoamine ligands. Indeed, these two Ag(Ⅰ)-Bi(Ⅲ) LFHDPs form smooth and uniform films ranging in thickness from 250 nm to 1 µm, with preferred orientations. Notably, the studies on the optical properties showed that the direct band gap value decreased from 2.17 eV to 1.91 eV for CAB-1 and from 2.05 eV to 1.86 eV for CAB-2 with increasing thickness. Accordingly, photo-current response using a xenon lamp revealed a significant difference of over 1000 nA between light and dark conditions for 1 µm-thickness films, suggesting potential for light harvesting. Other than that, thicker films of CAB-1 and CAB-2 exhibit high stability for 90 days in a relatively humid environment (RH of 55%), paving the way for promising optoelectronic applications.
Hyperforatone A (1), the 1,8-seco rearranged polycyclic polyprenylated acylphloroglucinol, possessed an unusual bicyclo[5.4.0]undecane skeleton bearing a 5/7/6/5 ring system, and two known biosynthetically related precursors (2 and 3) were isolated from Hypericum perforatum (St. John’s wort). The structure and absolute configuration were unambiguously confirmed by a combination of comprehensive spectroscopic data, computational methods including residual dipolar couplings (RDCs), and X-ray crystallography. Density functional theory (DFT) calculations revealed that the cationic cyclization reaction was key to proposed formation mechanism for hyperforatone A. Furthermore, in vitro and in vivo experiments demonstrated that compound 1 was a potential anti-neuroinflammatory agent.
The exploitation of organic-inorganic hybrid perovskites (OIHPs) as active layer materials for typical sandwich-structured resistive memories has attracted widespread interest due to the property of low power consumption and fast switching. However, the inherent thermal instability of perovskites limits the application of OIHPs-based resistive memories under extreme conditions, while the influence of thermal effects on their resistance change characteristics remains unclear. Herein, a novel 2D <100>-oriented high-temperature resistant OIHP [(BIZ-H)2(PbBr4)]n (BIZ = benzimidazole) is prepared as an active layer material to fabricate FTO/[(BIZ-H)2(PbBr4)]n/Ag resistive memory with excellent thermal reproducibility and stability up to 120 ℃. The increase in temperature leads to a decrease in the PbBr6 octahedral distortion in the crystal structure, an increase in hydrogen bonding between the (BIZ-H)+ cation and the (PbBr4)n2n- layer, and a shortening of the spacing of the inorganic layers, which is found to result in the creation and predominance of thermally activated traps with increasing temperature. This work provides a new direction for the next generation of OIHPs-based resistive memories with high-temperature tolerance.
Developing efficient electrocatalysts for oxygen evolution reaction (OER) is imperative to enhance the overall efficiency of electrolysis systems and rechargeable metal-air batteries operating in aqueous solutions. High-entropy materials, featured with their distinctive multi-component properties, have found extensive application as catalysts in electrochemical energy storage and conversion devices. However, synthesizing nanostructured high-entropy compounds under mild conditions poses a significant challenge due to the difficulty in overcoming the immiscibility of multiple metallic constituents. In this context, the current study focuses on the synthesis of an array of nano-sized high entropy sulfides tailored for OER via a facile precursor pyrolysis method at low temperature. The representative compound, FeCoNiCuMnSx, demonstrates remarkable OER performance, achieving a current density of 10 mA/cm2 at an overpotential of merely 220 mV and excellent stability with constant electrolysis at 100 mA/cm2 for over 400 h. The in-situ formed metal (oxy)hydroxide has been confirmed as the real active sites and its exceptional performance can be primarily attributed to the synergistic effects arising from its multiple components. Furthermore, the synthetic methodology presented here is versatile and can be extended to the preparation of high entropy phosphides, which also present favorable OER performance. This research not only introduces promising non-noble electrocatalysts for OER but also offers a facile approach to expand the family of nano high-entropy materials, contributing significantly to the field of electrochemical energy conversion.
A binary-mixed electron transport layer (ETL) has been reported for constructing solution-processable near-infrared organic light-emitting diodes (NIR OLEDs). Relative to the single-component ETL, the binary-mixed ETL composed of PDINN:TPBi can enhance the carrier transport capacity, reduce device impedance, and weaken fluorescence quenching of the emitting layer. By carefully selecting an appropriate luminescent material Y5 (a nonfullerene electron acceptor in organic solar cells) and precisely fine-tuning the molecular aggregation in active layer using a mixed solvent, the morphology is optimized and luminescence performance is enhanced, resulting in efficient NIR OLEDs with an emission peak at 890 nm. The experiment showcases a Y5-based near-infrared OLED with a maximum radiance of 34.9 W sr-1 m-2 and a maximum external quantum efficiency of 0.50%, which is among the highest values reported for non-doped fluorescent NIR OLEDs with an emission peak over 850 nm.
Redox dyshomeostasis is a critical factor in the initiation of numerous diseases, making the accurate evaluation of the redox status of the cellular environment an important aspect of physiological research. However, maintaining redox homeostasis relies on a complex and dynamic physiological system involving multiple substrate-enzyme interactions, so its accurately detection remains a challenge. With this research, we developed an activable fluorescence switching platform by incorporating different conjugate acceptors to a fluorophore using ester bonds and resulting in fluorescence quenching due to donor-excited photo-induced electron transfer (d-PeT), which was confirmed through density functional theory calculations. The reaction-based probe was deployed for recognizing all major intracellular reducing sulfur species (RSS), including H2S, cysteine (Cys), homocysteine (Hcy), glutathione (GSH), and protein free thiols. The quenched fluorescence was significantly recovered by RSS, through releasing the fluorophore and diminishing the d-PeT effect. Furthermore, the fluorescent probe was used for the sensing and imaging RSS in living cells, demonstrating good cell-permeability, low cytotoxicity, and negative correlation with reactive oxygen species content, enabling the evaluating of global thiols redox state in HepG2 cellular lines during ferroptosis processes.
Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction (MOR) performance can fundamentally guide high efficient catalyst design. Herein, density functional theory (DFT) calculations were performed at first to study the d–d orbital interaction of metallic PtPdCu, revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms. Under the theoretical guidance, PtPdCu medium entropy alloy aerogels (PtPdCu MEAAs) catalysts have been designed and systematically screened for MOR under acid, alkaline and neutral electrolyte. Furthermore, DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that PtPdCu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO2. For practical direct methanol fuel cells (DMFCs), the PtPdCu MEAAs-integrated ultra-thin catalyst layer (4–5 µm thickness) as anode exhibits higher peak power density of 35 mW/cm2 than commercial Pt/C of 20 mW/cm2 (~40 µm thickness) under the similar noble metal loading and an impressive stability retention at a 50-mA/cm2 constant current for 10 h. This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.
Gel-based sensors have provided unprecedented opportunities for bioelectric monitoring. Until now, sensors for underwater applicants have remained a notable challenge, as most sensors work effectively in air but swell underwater leading to functional failure. Herein, we introduce an innovative amphibian-inspired high-performance ionogel, where multiple supramolecular interactions in the ionogel's network confer good stretchability, elasticity, conductivity, and the hydrophobic C-F bonds play a key role in diminishing water molecule hydration and provide outstanding environmental stability. These unique properties of ionogels make them suitable as wearable amphibious flexible sensors, and the sensors are capable of highly sensitive and stable human motion monitoring in air and underwater. Integration of the designed sensor into an artificial intelligence drowning alarm system, which recognizes the swimmer's movement status by monitoring the amplitude and frequency, especially in the drowning status for real-time alarms. This work provides novel strategies for motion recognition and hazard monitoring in amphibious environments, meeting the new generation of wearable sensors.
Multiple donor-acceptor (D-A) combinations represent a promising category of thermally activated delayed fluorescence (TADF) materials, offering potential for superior efficiency and stability. However, current systems are predominantly composed of limited donor groups, primarily carbazole-based derivatives. In this work, we developed a series of D-A type materials incorporating helical π-expanded carbazole (CzNaph) and 7H-dinaphtho[1,8-bc:1′,8′-ef]azepine (AzNaph), alongside traditional carbazole, ranging from mono- to tetra-substituted configurations (Dn-A). Through systematic investigation of geometric and electronic structures, the number and positioning of multiple donors are confirmed with significant manipulations on charge transfer characteristics and the S1 state via steric effects. Density functional theory (DFT) calculations reveal that varying the number of π-extended donors within the acceptor framework produces emission colors from ultraviolet to red, providing a diverse range of emitters. Furthermore, the reduced reorganization energy of S1 observed in tetra-substituted Cz and CzNaph, as well as MonoAzN, indicates lower structural relaxation, highlighting these materials' potential as stable luminescent candidates. This study underscores the importance of diverse composing units in achieving efficient and stable TADF emitters with multiple and hetero-donor configurations.
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