Photophysical Characterization. The annihilators under investigation herein are presented in Figure alongside their respective absorption and fluorescence spectra. PPO, TIPS-Naph, TP, and 2,5-diphenyl-1,3,4-oxadiazole (PPD) have all been used for TTA-UC previously, while PPF and 2-phenylindene (2PI), to the best of our knowledge, are demonstrated as annihilators for the first time. These compounds all emit UV light efficiently, albeit with non-unity quantum yields (Table ), but their respective first singlet and triplet excited state energies are quite different, spanning 3.5-4.0 eV (singlets) and 2.1-2.8 eV (triplets, Table ). Even though this study is primarily conducted in toluene as the solvent, the absorption spectra in Figure are measured in THF since toluene absorption interferes with the spectral shape of annihilator absorption below 290 nm. To make comparison between annihilator species as feasible as possible we chose to use only one sensitizer. While cadmium sulfide nanocrystals have previously been used to sensitize high triplet energy annihilators such as PPD, their notoriously complex photophysics, the need for additional mediating compounds, and suboptimal performance when paired with annihilators with elevated triplet energies 30 caused us to search for molecular sensitizers with the capability to sensitize all annihilators used herein.