可见光光源，特别是低激发密度的可见光光源，如半导体LED、荧光灯及太阳光，激发的紫外光C段（UVC）上转换材料在无感标识与防伪、光催化、生物和城市环境领域的抗菌等方面具有巨大的应用潜力。可见光激发UVC上转换材料要求：发光中心第一激发态具有较长的能级寿命，且能有效吸收可见光光子；基质材料能有效透过可见光和UVC。由于外层电子的屏蔽作用，稀土离子具有丰富的、寿命较长的能级；高带隙无机材料可以有效透过UVC，因此稀土离子掺杂的无机发光材料是可见光激发UVC上转换荧光体的理想选择。然而可见光激发UVC上转换荧光体较低的发射效率限制了应用，如何提高低激发密度下的UVC上转换功率是当前面临的最大难题。着重介绍可见光激发的UVC上转换材料发展过程，当前的可见光激发UVC上转换的研究现状，低激发密度研究领域面临的挑战、解决途径和方法。

Ultraviolet C(UVC) upconversion phosphors excited by visible light sources, particularly those with low excitation densities, such as semiconductor LED, fluorescent lamps, and sunlight, have great potential in nonsensitive labeling, anticounterfeiting, photocatalysis, and biological and urban environmental antimicrobial fields. To achieve visible light excitation, UVC upconversion phosphors require a long energy level lifetime in the first excited state, the ability to effectively absorb visible light photons, and a host material that can effectively transmit visible light and UVC. Rare-earth ions are shielded by their outer electrons and have abundant energy levels with a long lifetime; inorganic materials with high band gaps can effectively penetrate UVC. Therefore, inorganic luminescent materials doped with rare-earth ions are ideal choices for UVC upconversion phosphors owing to visible light excitation. However, their low UVC upconversion emission power limits their application. Thus, the greatest problem currently faced is improving the UVC upconversion power under low excitation densities. This work focuses on the development of UVC upconversion phosphors for visible light excitation, the current research status, and research solutions and methods in the field of low excitation densities.