Sullivan, Colette M.Nienhaus, Lea2024-09-102024-09-102024Sullivan, C. M., & Nienhaus, L. (2024). Exploring Sensitized Photon Upconversion – From Past to Present. CHIMIA, 78(7–8), 518. https://doi.org/10.2533/chimia.2024.518https://hdl.handle.net/1911/117859The conversion of low energy photons into high energy photons via triplet-triplet annihilation (TTA) photon upconversion (UC) has become a promising avenue for furthering a wide range of optoelectronic applications. Through the decades of research, many combinations of triplet sensitizer species and annihilator molecules have been investigated unlocking the entire visible spectrum upon proper pairings of sensitizer and annihilator identities. Here, we reflect upon the seminal works which lay the foundation for TTA-UC originating from solution-based methods and highlight the recent advances made within the solid state primarily focusing on perovskite-based triplet generation.engExcept where otherwise noted, this work is licensed under a Creative Commons Attribution (CC BY) license.  Permission to reuse, publish, or reproduce the work beyond the terms of the license or beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Journal article2024_518https://doi.org/10.2533/chimia.2024.518