In recent years, carbon dots, graphene quantum dots, and other carbon nanocolloids have attracted a mounting interest as readily available, non-toxic, and tailorable carbon-based nanomaterials. One of the most fascinating features of carbon nanocolloids is their luminescence, the origin of which remains a source of dispute. The lack of understanding of the optical properties of carbon nanocolloids hampers their use in technological, environmental, and biomedical processes. Here, we review the current knowledge of excited states in carbon nanocolloids and related properties, inviting researchers to embrace the complexity of carbon nanocolloids. We point to the fundamental problems associated with their structure, photophysics, and photochemistry and highlight multiple directions of current and future research of this exciting class of nanomaterials.

近年来，碳点，石墨烯量子点和其他碳纳米胶体吸引了越来越多的兴趣，如易于获得的，无毒且可定制的碳基纳米材料。碳纳米胶体最引人入胜的特征之一就是它们的发光，其起源仍然是引起争议的原因。对碳纳米胶体的光学性质缺乏了解阻碍了它们在技术，环境和生物医学过程中的使用。在这里，我们回顾了碳纳米胶体及其相关性质的激发态的当前知识，邀请研究人员来拥抱碳纳米胶体的复杂性。我们指出了与它们的结构，光物理和光化学有关的基本问题，并突出了这一令人兴奋的纳米材料类别的当前和未来研究的多个方向。