Enhancement of Fluorescence Emission for Tricolor Quantum Dots Assembled in Polysiloxane toward Solar Spectrum-Simulated White Light-Emitting Devices

Organosilicon-Based Carbon Dots and Their Versatile Applications

Carbon dots (CDs) are a newly discovered type of fluorescent material that has gained significant attention due to their exceptional optical properties, biocompatibility, and other remarkable characteristics. However, single CDs have some drawbacks such as self-quenching, low quantum yield (QY), and poor stability. To address these issues, researchers have turned to organosilicon, which is known for its green, economical, and abundant properties. Organosilicon is widely used in various fields including optics, electronics, and biology. By utilizing organosilicon as a synthetic precursor, the biocompatibility, QY, and resistance to self-quenching of CDs can be improved. Meanwhile, the combination of organosilicon with CDs enables the functionalization of CDs, which significantly expands their original application scenarios. This paper comprehensively analyzes organosilicon in two main categories: precursors for CD synthesis and matrix materials for compounding with CDs. The role of organosilicon in these categories is thoroughly reviewed. In addition, the paper presents various applications of organosilicon compounded CDs, including detection and sensing, anti-counterfeiting, optoelectronic applications, and biological applications. Finally, the paper briefly discusses current development challenges and future directions in the field.

Facilely Direct Construction, White-Light Emission, and Color-Adjustable Luminescence of LaF3 :Pr3+ @SiO2 Yolk-Shell Nanospheres with Moisture Resistance

Poor water stability and single luminous color are the major drawbacks of the most phosphors reported. Therefore, it is important to realize multicolor luminescence in a phosphor with single host and single activator as well as moisture resistance. LaF3 :Pr3+ @SiO2 yolk-shell nanospheres are facilely obtained by a designing new technology of a simple and cost-effective electrospray ionization combined with a dicrucible fluorating technique without using protective gas. In addition, tunable photoluminescence, especially white-light emission, is successfully obtained in LaF3 :Pr3+ @SiO2 yolk-shell nanospheres by adjusting Pr3+ ion concentrations, and the luminescence mechanism of Pr3+ ion is advanced. Compared with the counterpart LaF3 :Pr3+ nanospheres, the water stability of LaF3 :Pr3+ @SiO2 yolk-shell nanospheres is improved by 15% after immersion in water for 72 h, and the fluorescence intensity can be maintained at 86% of the initial intensity. Furthermore, by treating the yolk-shell nanospheres with hydrofluoric acid, it is not only demonstrated that the shell-layer is SiO2 but also core-LaF3 :Pr3+ nanospheres are obtained. Particularly, only fluorination procedure among the halogenation can produce such special yolk-shell nanospheres, the formation mechanism of yolk-shell nanospheres is proposed detailedly based on the sound experiments and a corresponding new technology is built. These findings broaden practical applications of LaF3 :Pr3+ @SiO2 yolk-shell nanospheres.

Organosilicon Fluorescent Materials

In the past few decades, organosilicon fluorescent materials have attracted great attention in the field of fluorescent materials not only due to their abundant and flexible structures, but also because of their intriguing fluorescence properties, distinct from silicon-free fluorescent materials. Considering their unique properties, they have found broad application prospects in the fields of chemosensor, bioimaging, light-emitting diodes, etc. However, a comprehensive review focusing on this field, from the perspective of their catalogs and applications, is still absent. In this review, organosilicon fluorescent materials are classified into two main types, organosilicon small molecules and polymers. The former includes fluorescent aryl silanes and siloxanes, and the latter are mainly fluorescent polysiloxanes. Their synthesis and applications are summarized. In particular, the function of silicon atoms in fluorescent materials is introduced. Finally, the development trend of organosilicon fluorescent materials is prospected.

Hydrophobic expanded graphite-covered support to construct flexible and stable SERS substrate for sensitive determination by paste-sampling from irregular surfaces

Surface enhanced Raman spectroscopy (SERS) is a promising technique for trace determination. More and more attention is focused on hybrid SERS substrates, which coupled with noble metal nanoparticles and carbon-based materials. Herein, expanded graphite (EG) is used to prepare EG-covered support by ultrasonic washing and filtration. Such support is flexible and can be cut into any shape. And the contact angle (θe) for Au nanorods (Au NRs) sol on the EG-covered support was 108.2° and the hydrophobic surface is helpful for Au NRs to construct 'hot spots' during evaporation. The limits of detection (LOD) for crystal violet (CV), thiram, malachite green (MG) and methylene blue (MB) were as low as 1 ppb, 50 ppb, 1 ppb and 1 ppb, respectively. Moreover, a fast and convenient 'paste-sampling' method could be employed for trace contaminants on real samples, because EG-based Au NRs substrate is of flexibility and porosity. Thus, CV residue on shrimp could be determined lower than 1 ppb and thiram residue on grapes could be identified lower than 50 ppb. In addition to high sensitivity, the stability of EG-based Au NRs substrate is also very good. Even after acid/alkali pretreatment (pH = 4∼10) or 30 min of thermal treatment (T = 20∼100 °C), the enhancement of the substrate remained stable. What's more, the substrate could be stored as long as 30 days. The highly stable, sensitive, cost-effective and easy-to-produce EG-based Au NRs substrates exhibit a great potential to promote application of SERS for routine analysis.

Silane-Functionalized Carbon Dots and Their Polymerized Hybrids: From Optoelectronics to Biotherapy

Nanomaterials usually manifest unique properties in solutions but will be undermined in the solid state. It is necessary to incorporate them into substrates or hybrid them with other functional materials for multiple devices and applications. Though there are a variety of methods to inherit their intrinsic properties like fluorescent and mechanical performance, most nanohybrid materials would lose their transparency irreversibly when construct solid-state devices. As a hot topic of nanomaterials in recent years, scientific works found a type of carbon dots using silane coupling agents as precursors that can overcome the shortcoming. These carbon dots, called silane-functionalized carbon dots (SiCDs), are catching increasing interest due to their versatility. Silane coupling agents endow SiCDs with the ability to disperse in solvents or polymerize with matrices by blending or covalent bonds without loss of transparency and decline of performance. The distinguishing features make SiCDs an ideal high transmittance, high doping concentration nanomaterial. The synergistic effect of SiCDs and hybridized sol-gel solid structures can not only hold the optical features of CDs but also enhance their original physical and chemical performance. This highlight focuses on the connection between SiCDs and organosilanes. Plus, preparation methods, applications, and prospective of SiCDs are mentioned.

Ultralow Threshold Lasing from Carbon Dot-Ormosil Gel Hybrid-Based Planar Microcavity

The absence of an ideal solid matrix with resistance to harsh conditions for carbon dots (CDs) and high transmittance in the visible/near infrared region is the bottleneck in CD applications. In this study, we show that a stable rigid structure can be formed between CDs and organically modified silicates (ormosil) gel when CDs are incorporated into ormosil gel hybrids as a solid matrix. A high photoluminescence quantum yield (PLQY) of 63% is achieved at a 583 nm emission. Peak optical gain of the hybrids was found to be 67 cm^-1 at peak wavelength. Ultralow threshold (~70 W/cm²) lasing can also be demonstrated from a planar microcavity by using CD-ormosil gel hybrids as a gain medium.

Magic-Sized Stoichiometric II-VI Nanoclusters

Metal chalcogenide nanomaterials have gained widespread interest in the past two decades for their potential optoelectronic, energy, and catalytic applications. The colloidal growth of various forms of these materials, such as nanowires, platelets, and lamellar assemblies, proceeds through certain thermodynamically stable, ultrasmall (<2 nm) intermediates called magic-sized nanoclusters (MSCs). Due to quantum confinement and its resultant intriguing properties, isolation or direct synthesis of MSCs and their structure characterization, which is very much challenging, are current topics of fundamental and applied scientific research. By comprehensive understanding of the structure-activity relationships in MSCs, the nucleation and growth processes can be manipulated, resulting in the synthesis of novel metal chalcogenide materials for various applications. This review focuses on recent advances in the chemical synthesis, characterization, and theoretical calculations of CdSe and its related II-VI nanoclusters. It highlights the studies of photophysical and magneto-optical properties as well as heteroatom doping of MSCs followed by their chemical transformation to high-dimensional nanostructures. At the end of the review, future directions and possible ways to overcome the challenges in the research of semiconductor MSCs are also presented.

White-light-emitting triphasic fibers as a phosphor for light-emitting diodes

White-light-emitting materials have received significant attention because of their potential application in lighting, displays, and sensors. However, it is a challenge to obtain white light from one phosphor, because the basic requirement of the white light emission spectrum is that it should be wide enough to cover the entire visible light region. In this study, we have designed and demonstrated a white-light-emitting PMMA-CBS-127/PVP-coumarin 6/PAN-rhodamine B (PSCR) fibrous membrane, which was prepared through a triphasic electrospinning method. Three luminescent organic dyes, CBS-127 (4.77 wt%, blue), coumarin 6 (0.1 wt%, green), and rhodamine B (0.42 wt%, red), were elaborately selected and doped into PMMA, PVP, and PAN, respectively. The resulting flexible PSCR membranes show white light emission (cover the entire visible-light region from 382 to 700 nm) with Commission Internationale de L'Eclairage (CIE) coordinates of (0.31, 0.32), which is very close to ideal white light with CIE coordinates (0.33, 0.33). In addition, the PSCR membranes maintained high-quality white light emission after about 10 weeks of storage. The PSCR membranes can be used as the phosphor converting layer in white light-emitting diodes (WLEDs) through a remote membrane packaging method. A bright white emission is achieved at an applied voltage of 9 V. Therefore, the results indicate that PSCR membranes are potentially attractive candidates for application in WLEDs and displays.