Visible-to-UV Photon Upconversion: Recent Progress in New Materials and Applications

Ultraviolet (UV, lambda<400 nm) light is essential for various photochemical reactions, but its intensity in the solar spectrum is very low, and light sources that artificially generate high-energy UV light are inefficient and environmentally unfriendly. A solution to this problem is photon upconversion (UC) from visible (vis, lambda>400 nm) light to UV light. Among several mechanisms, UC based on triplet-triplet annihilation (TTA-UC) in particular has made remarkable progress in recent years. The development of new chromophores has enabled highly efficient conversion of low-intensity visible light into UV light. In this review, we summarize the recent development of visible-to-UV TTA-UC, from the development of chromophores and their production into films to their application in various photochemical processes such as catalysis, bond activation and polymerization. Finally, challenges and opportunities in future material development and applications will be discussed.

Automated summary

Recently, significant progress has been made in visible-to-UV photon upconversion (TTA-UC) based on triplet-triplet annihilation (TTA) mechanism. The development of new chromophores has greatly improved the efficiency of converting low-intensity visible light into UV light. This review summarizes the recent advancements in visible-to-UV TTA-UC, including chromophore development, film production, and their applications in catalysis, bond activation, and polymerization. The challenges and opportunities in future material development and applications are also discussed.