Search Results (203)

The design of nanoscale electronic components remains a major challenge because we have limited control over the chemical and physical properties of their molecular constituents. Even subtle structural or compositional modifications can significantly alter their electronic behavior. Consequently, updating a molecular component often necessitates developing a new model from scratch. In this study, we present a comprehensive analysis of the rectification properties of a promising molecular diode initially proposed by Aviram and Van Dyck. The model has been systematically decomposed into fundamental building blocks, enabling the electron transport process to be examined both as an integrated event and as a sum of cooperative interactions. Our findings reveal that certain motifs—such as the D-σ-A architecture—play a significant role in rectification. However, achieving high-performance molecular rectifiers also requires cooperative interplay with other structural elements that contribute to rectification, such as asymmetric molecule–metal contacts. In this study, we conduct a detailed investigation of the roles these elements play in shaping the rectifying characteristics, and we further interpret their effects by analyzing the dominant transport channels under forward and backward bias conditions. This deeper understanding of the transport mechanism offers greater control over the system and opens the door for rational design strategies for improving rectification efficiency in future molecular devices. Full article

Biogenic amines (BA) are simple organic bases of low molecular weight, formed during decarboxylation of amino acids. Ripened cheeses provide suitable conditions for the development of bacteria and production of BAs. The aim of the present study was to investigate the presence of eight BAs in ripened cheese samples (n = 125) using a high-performance liquid chromatography with diode array detector (HPLC-DAD). Furthermore, microbiological analyses towards identification of bacteria using matrix-assisted laser desorption ionisation—time of flight mass spectrometry (MALDI-TOF MS) were performed. Cadaverine and putrescine were detected in 28.0% and 20.8% of cheese samples at concentrations ranging from 6.12 to 2871 mg/kg and 5.74 to 441 mg/kg, respectively. High amounts of putrescine and cadaverine in cheeses were associated with the presence of Hafnia alvei. Tyramine was identified in 28.0% of samples in the concentration range of 5.62–646 mg/kg. High concentrations of this amine was found in cheeses containing Enterococcus faecium and Enterococcus faecalis. Histamine content, the only BA restricted in food according to Regulation 2073/2005, was observed above 100 mg/kg in 11.2% of the cheeses. Ripened cheeses available on the local retail market may contain significant levels of biogenic amines and may pose a potential health hazard to consumers. Full article

The application of organic light-emitting diodes (OLEDs) has become widespread, with polarizers commonly employed to mitigate the influence of external light sources on OLED displays. However, when the light signal generated by the OLED emissive layer passes through the polarizer, approximately 50% of the light energy is inevitably lost. Circularly polarized luminescent (CPL) molecules, capable of emitting specific left- or right-handed circularly polarized light, theoretically enable 100% light energy utilization in corresponding OLED devices (CP-OLEDs). With this breakthrough, CPL mechanisms exhibit significant potential for applications in data storage, bioimaging, and 3D displays. In this review, we focus on molecules constructed via a chiral perturbation strategy, analyzing their CPL generation mechanisms and molecular engineering principles. The relationship between these molecular structures and OLED performance is systematically analyzed and summarized. Finally, we critically address current challenges in developing both CPL active materials and devices based on the chiral perturbation strategies, while providing perspectives on future developments and potential challenges in this field. Full article

Natural colorants, with their sustainable origins, offer a promising alternative for various applications. Advanced studies have unveiled the remarkable properties, resilience, and durability of these ancient dyes, which our ancestors developed through sustainable material processing. This serves as a testament to the potential of sustainable solutions in our field. As part of our research, we prepared three medieval temperas using gum arabic, parchment glue, and casein glue. These tempera were explicitly designed to protect the purples obtained from Chrozophora tinctoria extracts. A comprehensive multi-analytical approach guides our research on natural colorants. Central to this approach is the use of molecular fluorescence by microspectrofluorimetry, a key tool in our study. By analyzing the emission and excitation spectra in the visible range, we can identify specific formulations. This method is further supported by fingerprinting techniques, including Fourier Transform Infrared Spectroscopy (FTIR) and High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD). These are further complemented by Fiber Optics Reflectance Spectroscopy (FORS) and colorimetry. Building on our understanding of orcein purples, we have extended our research to purples derived from Chrozophora tinctoria extracts. Our findings reveal the unique properties of Chrozophora tinctoria, which can be accurately distinguished from orcein purples, highlighting the distinctiveness of each. Full article

In controlled environment agriculture (CEA), supplementary lighting, particularly light-emitting diode (LED) technology, is essential for optimizing plant growth and development. Among the spectral components, blue light (400–500 nm) plays an important role in affecting plant morphogenesis, photosynthesis, and key physiological processes. However, species-specific guidelines for optimizing blue light parameters such as intensity, duration, and spectral ratios remain insufficiently developed. Furthermore, plant spectral requirements shift across developmental stages, highlighting distinct blue light management strategies for each phase. This review synthesizes existing knowledge on the impacts of blue light on morphological adaptation, photosynthetic efficiency, flowering, and secondary metabolism, with an emphasis on differential responses across diverse plant species. We emphasize the need for growth-stage-specific lighting protocols and scalable strategies applicable to commercial CEA systems. Interdisciplinary collaboration, integrating molecular biology, genomics, and horticultural engineering, is necessary to enhance understanding of blue light-driven regulatory networks, optimize photoreceptor responses, and facilitate systematic validation of adaptive lighting approaches, ultimately advancing sustainable horticulture and next-generation CEA innovations. Full article

A tetradentate Pt(II) complex with a 5/6/6 structural backbone, Pt(PhPiPy-O-PytmCz), was synthesized by incorporating two distinct cycloalkyl groups. These structural modifications significantly enhanced the photoluminescence quantum yield and effectively increased the distance between molecules, thereby mitigating undesirable intermolecular interactions and triplet-state quenching. This strategic molecular design resulted in an external quantum efficiency of 11.5% at a wavelength of 539 nm and significantly enhanced operational lifetimes in green phosphorescent organic light-emitting diodes (OLEDs). These findings are expected to inspire the development of new green luminescent materials and innovative strategies in OLED technology. Full article

Recent advancements in thermally activated delayed fluorescence (TADF) materials and mechanochromic materials have significantly enhanced the efficiency and versatility of light-emitting electrochemical cells (LECs) and organic light-emitting diodes (OLEDs). TADF materials have enabled efficiency improvements, achieving an internal quantum efficiency (IQE) of nearly 100% by utilizing both singlet and triplet excitons. Meanwhile, mechanochromic materials exhibit reversible optical changes upon mechanical stimuli, making them promising for stress sensing, encryption, and flexible electronics. The synergistic integration of TADF and mechanochromic materials in OLEDs and LECs has led to enhanced efficiency, stability, and multifunctionality in next-generation lighting and display technologies. This narrative review explores recent breakthroughs in devices that incorporate both TADF and mechanochromic materials as emitters. Particular attention is given to the molecular design that enable both TADF and mechanochromic properties, as well as optimal device structures and performance parameters. Moreover, this review discusses the only LEC fabricated so far using a TADF-mechanochromic emitter, highlighting its performance and potential. Finally, the report concludes with an outlook on the future commercial applications of these materials, particularly in wearable electronics and smart display technologies. Full article

A zinc complex bearing a pyrazolone-based azomethine ligand has been synthesized for blue-emitting organic light-emitting diodes (OLEDs). The azomethine ligand H₂L and the complex [ZnL·H₂O] were characterized by IR, 1H NMR, XRD, and TGA/DSC techniques. According to a single-crystal X-ray diffraction analysis, the complex [ZnL·H₂O] has a molecular structure. Its solid-state PL maxima appear to be at 416 nm and emit moderate blue emission with a quantum yield (QY) of 2%, with a dehydrated form of the complex showing greater efficiency with a QY of 55.5%. ZnL-based electroluminescent devices for OLED applications were fabricated. The devices exhibit blue emission with brightness up to 5300 Cd/A. Full article

We report the molecular design and synthesis of a novel selenium-containing multi-resonance thermally activated delayed fluorescence (MR-TADF) host material, 3,6-di-tert-butyl-9,16-dioxa-15-selena-4b-boraindeno[2,1-a]naphtho[3,2,1-de]anthracene (TDBA-SePh), for green and red phosphorescent organic light-emitting diodes (PhOLEDs). By incorporating selenium into the DOBNA-based MR-TADF backbone, the reverse intersystem crossing (RISC) process was effectively activated, leading to enhanced utilization of triplet excitons. The corresponding RISC rate was determined to be 3.91 × 10⁴ s⁻¹. When applied to PhOLED devices, TDBA-SePh-based green and red OLEDs exhibited higher external quantum efficiency (EQE) and reduced efficiency roll-off compared to conventional mCP-based host materials. At a luminance of 1000 cd m⁻², the green and red devices exhibited roll-off values of 2.5% and 4.3%, respectively. This improvement is attributed to the incorporation of selenium as a heteroatom, which accelerates the RISC process, thereby suppressing triplet-triplet annihilation (TTA). These results suggest that adopting a similar molecular design strategy can not only reduce efficiency roll-off but also enhance device efficiency and operational stability, offering significant potential for future OLED applications. Full article

Blue exciplexes, a critical innovative component in organic light-emitting diodes (OLEDs) technology, exhibit substantial potential for enhancing device efficiency, reducing driving voltage, and simplifying structural designs. This article reviews the pivotal role of blue exciplexes in OLEDs, analyzing their unique advantages and challenges as emitters and host materials. Through optimized molecular design, blue exciplexes achieve high color purity and emission efficiency, surpassing conventional fluorescent materials. Additionally, their wide energy bands and high triplet energy provide opportunities to improve the performance of sky-blue, deep-blue, and white OLEDs. However, limitations in deep-blue efficiency, material degradation due to high-energy excitons, and spectral red-shift pose significant challenges to their development. This review offers a comprehensive perspective and research reference on the photophysical mechanisms of blue exciplexes and their applications in display and lighting fields. Full article

The mixotrophic dinoflagellate Akashiwo sanguinea is known to have acute toxic effects on multiple marine organisms, while the composition and chemical properties of its toxins remain unclear. In this study, we established a method for separation and purification of A. sanguinea toxins using chromatographic techniques. The acetone extract of A. sanguinea exhibited higher hemolytic activity and shorter incubation time compared to methanol and ethyl acetate extracts. Five fractions were obtained by solid-phase extraction (SPE), of which SPE3 (acetone/water ratio 3:2) and SPE4 (acetone/water ratio 4:1) exhibited the highest hemolytic activities and allelopathic effects. Further purification on SPE3 and SPE4 using reverse-phase high-performance liquid chromatography (RP-HPLC) coupled with a diode array detector (DAD) resulted in 11 subfractions, among which Fr4-5 displayed the strongest hemolytic activity. Nearly all active subfractions exhibited higher hemolytic activities incubated under light than those in the dark (p < 0.05), suggesting that A. sanguinea can produce both photosensitive and non-photosensitive toxins, with the former being the primary contributors to its hemolytic activity. Molecular characterization by UV-Vis, FTIR, and HRMS/MS analysis revealed that the structural features of Fr4-5 were highly consistent with porphyrin analogs and could be derived from chlorophyll c-related precursors. These findings highlight that the photosensitive toxins in A. sanguinea may serve dual roles in stress adaptation and ecological competition, potentially contributing to the formation of the blooms. Full article

In this paper, we present a one-step low-temperature solution combustion synthesis (SCS) of CuS nanoparticulated functional films processed via a simple blade-coating technique. This SCS route uses thiourea as a fuel and sulfur source, combined with copper(II) nitrate as an oxidant and a cupric ion source in an aprotic solvent such as non-toxic DMSO. It is hereby shown that the proposed SCS process formed a stable and completely dissolved molecular ink of thiourea and copper ion complexes, crucial for obtaining the pure crystalline phase of CuS nanoparticles (NPs). The CuS was formed by calcination at a low temperature of 200 °C during a brief annealing time of 20 min, to promote the synthesis of ~10 nm CuS NPs. The obtained CuS NPs were thoroughly analyzed in terms of structure and optoelectronic properties using various analytic and spectroscopic techniques, including TGA, XRD, FE-SEM, EDS, AFM, and four-point probe electrical resistivity measurements. The functionality of the prepared CuS nanoparticulated interlayers was evaluated by incorporating them as a hole injection layer (HIL) in Super Yellow (SY) organic light-emitting diodes (OLEDs). Full article

The narrow bandgap InN material, with exceptional physical properties, has recently gained considerable attention, encouraging many scientists/engineers to design infrared photodetectors, light-emitting diodes, laser diodes, solar cells, and high-power electronic devices. The InN/Sapphire samples of different film thicknesses that we have used in our methodical experimental and theoretical studies are grown by plasma-assisted molecular-beam epitaxy. Hall effect measurements on these samples have revealed high-electron-charge carrier concentration, η. The preparation of InN epifilms is quite sensitive to the growth temperature T, plasma power, N/In ratio, and pressure, P. Due to the reduced distance between N atoms at a higher P, one expects the N-flow kinetics, diffusion, surface components, and scattering rates to change in the growth chamber which might impact the quality of InN films. We believe that the ionized N, rather than molecular, or neutral species are responsible for controlling the growth of InN/Sapphire epifilms. Temperature- and power-dependent photoluminescence measurements are performed, validating the bandgap variation (~0.60–0.80 eV) of all the samples. High-resolution X-ray diffraction studies have indicated that the increase in growth temperature caused the perceived narrow peaks in the X-ray-rocking curves, leading to better-quality films with well-ordered crystalline structures. Careful simulations of the infrared reflectivity spectra provided values of η and mobility μ, in good accordance with the Hall measurements. Our first-order Raman scattering spectroscopy study has not only identified the accurate phonon values of InN samples but also revealed the low-frequency longitudinal optical phonon plasmon-coupled mode in excellent agreement with theoretical calculations. Full article

The enhancement of organic light-emitting diode (OLED) device performance has been a key area of research in organic optoelectronic devices. Optimizing carrier mobility within OLED devices is a crucial strategy. In this study, the hole transport layer was optimized using a self-assembled monolayer (SAM) subjected to different annealing temperatures. Through submitting the SAM to an annealing temperature of 100 °C, a maximum luminous intensity of 32,290 cd/m² and a maximum EQE of 1.77 were achieved, the latter being more than two-fold higher than that without the SAM. As the SAM annealing temperature increased from 80 °C to 120 °C, both the vertical orientation of molecules in the hole transport layer and the hole mobility in hole-only devices (HODs) improved. This vertical orientation is beneficial to enhancing hole mobility. Electrochemical impedance spectroscopy and surface morphology analysis revealed that the introduction of a SAM leads to the formation of interface resistance. The synergy effect between the variation in the molecular transition dipole moment and the interface morphology of the hole transport layer optimizes the hole mobility of HODs and leads to the enhancement of OLED performance. Full article

The organic light-emitting diode (OLED) has been regarded as the most prominent product in the current market of organic electronics, which has attracted growing attention because of their applications in full-color displays and solid-state lighting. Organic materials that exhibit strong luminescence in the solid state constitute the core position of OLED. Extensive research efforts to probe the structure of organic luminescent materials have attracted considerable attention to the conjugated fusion ring architecture. This is because it can confer molecular rigidity and helps to inhibit intermolecular interactions and non-radiative transitions, thus enhancing the performance of luminescent materials. Here, we use an efficient and simple method to construct an eight-membered ring molecular framework based on carbazole. Moreover, we have introduced groups with different electron-withdrawing abilities to develop a series of luminescent molecules. The results show that the nonplanar structure based on the eight-membered ring suppresses fluorescence quenching caused by molecular aggregation. As the doping concentration increases, the electroluminescence spectrum remains basically unchanged, indicating that the eight-membered ring structure can effectively suppress the intermolecular interaction. Notably, DCBz-pm exhibits deep blue emission with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.158, 0.046), which nearly meets the BT. 2020 standards. The DCBz-CN device reaches a maximum external quantum efficiency (EQE) of 4.36%. These results offer a new design strategy for improving the performance of OLEDs. Full article