Nanoengineering Triplet-Triplet Annihilation Upconversion: From Materials to Real-World Applications

Using light to control matter has captured the imagination of scientists for generations, as there is an abundance of photons at our disposal. Yet delivering photons beyond the surface to many photoresponsive systems has proven challenging, particularly at scale, due to light attenuation via absorption and scattering losses. Triplet-triplet annihilation upconversion (TTA-UC), a process which allows for low energy photons to be converted to high energy photons, is poised to overcome these challenges by allowing for precise spatial generation of high energy photons due to its nonlinear nature. With a wide range of sensitizer and annihilator motifs available for TTA-UC, many researchers seek to integrate these materials in solution or solid-state applications. In this Review, we discuss nanoengineering deployment strategies and highlight their uses in recent state-of-the-art examples of TTA-UC integrated in both solution and solid-state applications. Considering both implementation tactics and application-specific requirements, we identify critical needs to push TTA-UC-based applications from an academic curiosity to a scalable technology.

Automated summary

Using light to control matter has long been a goal for scientists, and triplet-triplet annihilation upconversion (TTA-UC) may provide a solution by converting low energy photons to high energy photons. This process allows for precise generation of high energy photons, overcoming challenges of light attenuation. Researchers are exploring various sensitizers and annihilators for TTA-UC in solution and solid-state applications. This review discusses deployment strategies and recent examples of TTA-UC, identifying critical needs to advance it from an academic curiosity to a scalable technology.