Research Progress on Synthesis, Regulation and Applications of Long-wavelength Emission Carbon Dots

In recent years，with the development of carbon dots in terms of synthesis routes，reaction mechanisms，and optical properties，a large amount of work has focused on carbon dots that emit long wavelengths such as infrared or near-infrared. Long wavelength refers to the red or near-infrared spectral region whose emission range is 600-1 800 nm. Compared with short-wavelength carbon dots，they have the characteristics of deep tissue penetration，less autofluorescence，long fluorescence lifetime and less light damage，and can be further applied in the fields of biomedical treatment，optoelectronics and optical device preparation. Therefore，in-depth exploration of the design and synthesis of long-wavelength emitting carbon dots is of great significance for their development and wide application. This article reviews the research progress of long-wavelength carbon dots in recent years，and introduces how to prepare long-wavelength carbon dots from two aspects：carbon source selection and control of optical properties. For example，choose some aliphatic compounds containing more amino groups and aromatic compounds with conjugated structures. And its optical properties can be controlled through changing the effective conjugation length，surface modification，and heteroatom doping. Finally，the latest research and future challenges of long-wavelength carbon dots in some fields such as biomedicine，LED optics，encryption and anti-counterfeiting are introduced. © 2024 Editorial Office of Chinese Optics. All rights reserved.