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.

One-pot synthesis of double silane-functionalized carbon dots with tunable emission and excellent coating properties for WLEDs application

Silane-functionalized carbon dots (SiCDs) can be exploited as effective color converting materials for the solid-state light-emitting devices. However, most of SiCDs reported thus far have shown photoluminescence emissions in the blue and green spectral range, which limit them to construct an efficient white light-emitting diodes (WLEDs) due to the lack of long-wavelength emission. Herein, a series of double silane-functionalized carbon dots (DSiCDs) were prepared via a one-step solvothermal method. The results show that the organic functional group of the silane has great influence on the optical properties of DSiCDs and the number of alkoxy group in the silane has great influence on coating properties of DSiCDs. In addition, the DSiCDs prepared by (3-aminopropyl)triethoxysilane and N-[3-(trimethoxysilyl)propyl]ethylenediamine with molar ratio of 7:3 show excellent optical properties with the maximum emission at 608 nm under 570 nm excitation. Furthermore, they can be completely cured within 1 h at room temperature to form fluorescent coating with high stability and strong adhesion to the substrate. Together with their excellent optical and coating properties, they can be directly coated on LED chips to prepare WLEDs, with a CIE coordinate of (0.33,0.31), color rendering index of 81.6, and color temperature of 5774 K.

Efficient full-color emitting carbon-dot-based composite phosphors by chemical dispersion

Realizing full-color emission plays a key role in exploring the luminescence mechanisms of carbon dots (CDots) and promoting the applications of CDots in light-emitting diodes (LEDs). Herein, a synthesis strategy for full-color emitting CDots was developed through the solvothermal reaction of citric acid and urea with a constant mass ratio but varying reactant concentrations in solvent. With the reactant concentrations increasing, a dual regulation mechanism including an enhanced nucleation growth process and subsequently increased C[double bond, length as m-dash]O/C[double bond, length as m-dash]N-related surface states should be responsible for the photoluminescence (PL) shift of CDots from blue to red. Relying on the hydrolyzation and condensation processes of 3-aminopropyltrimethoxysilane, a simple and universal method was developed by chemically dispersing the CDots into a cross-linked silica network on the surface of SiO₂ nanoparticles to produce efficient full-color emitting SiO₂/CDot composite phosphors with considerable PL quantum yields in the range of 30-60%. It was proved that the full-color emitting SiO₂/CDot composite phosphors could be flexibly applied in packaging white LEDs, releasing pure white light at the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.33) with a color rendering index (CRI) of 80.4 and a high color-rendering white light coming entirely from CDots with the CIE coordinates of (0.34, 0.36) and a CRI of 97.4, indicating promising application of the full-color emitting SiO₂/CDot composite phosphors in the LED field.

Carbon Dots: Diverse Preparation, Application, and Perspective in Surface Chemistry

Carbon dots (CDs) are a novel class of nanoparticles with excellent properties. The development of CDs involves versatile synthesis, characterization, and various applications. However, the importance of surface chemistry of CDs, especially in applications, is often underestimated. In fact, the study of the surface chemistry of CDs is of great significance in the explanation of the unique properties of CDs as well as the pursuit of potential applications. In this feature article, we do not only introduce the development of CDs in our group but also highlight their applications where surface chemistry plays a critical role.