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White light illumination is essential in daily life, however, the substantial amount of blue light it contains can damage human eyes. Therefore, it is important to block this high-energy blue light to protect visual health. In this study, yellow-emitting carbon dots (CDs) with a quantum yield exceeding 94% were synthesized using citric acid and urea. These CDs effectively absorb blue light. By incorporating them into polystyrene, multiple films termed CDs-based blue light blocking films (CBFs) were developed, each offering different levels of blue light absorption. These CBFs exhibited excellent transparency and efficient blue light filtering capabilities. This study highlights the potential of high quantum yield CDs, which specifically absorb blue light, as foundational materials for developing light-blocking solutions against high-energy short-wavelength light.

Carbon dots (CDs), due to their low cost, high stability, and high luminous efficiency, have emerged as an excellent material for the emissive layer in next-generation electroluminescent light-emitting diodes (ELEDs). However, improving the efficiency of fluorescent CDs-based ELEDs remains challenging, primarily because it is difficult to utilize triplet excitons in the electroluminescence process. Therefore, enhancing the exciton utilization efficiency of CDs during electroluminescence is crucial. Based on this, we exploited the characteristic large exciton binding energy commonly found in CDs to develop exciton-emitting CDs. These CDs facilitate the radiative recombination of excitons during electroluminescence, thereby improving the electroluminescent efficiency. By rationally selecting precursors, we developed high quantum efficiency CDs and subsequently constructed CDs-based ELEDs. The blue-light device exhibited an external quantum efficiency of over 4%. This study introduces a novel design concept for CDs, providing a new strategy for developing high-performance blue ELEDs based on CDs.

Carbon dots (CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental properties of the CDs are results of investigations conducted in the solution state, which may be completely different from those conducted in the solid state. In this work, we study the luminescence properties, photostability, and the dynamics of CDs in different matrix environments, from ensemble to the single-particle level. We observed that the properties associated with the emission centers and photostability of CDs were extremely sensitive to the local chemical environment. A better understanding of the dependence of the spectroscopic properties of CDs on the complex local chemical environment is an important step toward finding new ways of controlling the optical properties of CDs and optimizing their use in various applications.

Carbon dots (CDs), novel luminescent zero-dimensional carbon nanomaterials, have been widely applied due to their low toxicity, optimal optical properties, and easy modification. However, the current controllable equipment and mechanism explanation of CDs are relatively vague and require urgent resolution. Full-color emission CDs, an essential CDs category, have attracted people's attention given their light and color-tunable properties. In addition to a wider range of biological and optoelectronic device applications, full-color emission CDs have similar structures and significantly affected the fluorescence mechanism of CDs. At present, few studies have reported on the summary research of CDs emitted by its full color, which greatly limits the development of CDs mechanisms and applications. As such, the present review detailed the full-color CDs development status, to which a suitable method for preparing full-color CDs was presented and the existing fluorescence emission mechanism of full-color CDs was summarized. Herein, we comprehensively introduced full-color CDs applications in biology and optoelectronics. Finally, we made an outlook on the development and potential applications of full-color CDs. The present review aims to contribute novel insights and methods for understanding full-color CDs.