Photon upconversion is the process by which two low energy photons combine to form one higher energy photon. Traditional methods for upconversion require high-intensity, coherent light for efficient upconversion. In contrast, triplet-triplet annihilation upconversion (TTA-UC) can use low-intensity, incoherent light, such as that emitted from the sun. Currently, TTA-UC is limited by relatively low efficiencies and small anti-Stokes shifts, i.e. the energy gained during the upconversion process.. The focus of this project is to maximize the efficiency of upconversion through use of a triplet sensitizer with increased rate of intersystem crossing (ISC) and to maximize the anti-Stokes shift by minimizing the energy loss in both ISC and in triplet-triplet energy transfer (TTET) to the emitter. Thermally activated delayed florescence (TADF) sensitizers were used due to their small energy loss (<0.1 eV) during ISC compared to traditional platinum-based triplet sensitizers (ca. 0.7 eV loss). Further energy losses during triplet-triplet energy transfer (TTET) were minimized by appropriate matching of triplet levels of the sensitizer and emitter. Photoluminescence spectra were taken for mixed benzene solutions using 4CzIPN as the triplet sensitizer (50µM) and naphthalene or p-terphenyl as the emitter (25mM). Anti-Stokes shifts of 1.1 eV and 0.9 eV were observed for the solutions of 4CzIPN/Naphthalene and 4CzIPN/p-terphenyl, respectively. In the future, measurements will be made on solutions of both emitters with 4CzIPN-Br as the sensitizer, which has a greater rate of ISC. This will reveal how the efficiency of upconversion increases by increasing the rate of ISC. By addressing issues in efficiencies and in the maximization of the anti-Stokes shift, this project aims to push TTA-UC toward commercial viability.