Optoelectronic Applications of Thermally Activated Delayed Fluorescence

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The discovery of thermally activated delayed fluorescence (TADF) has sparked a revolution in the science and engineering of luminescent materials. These materials allow for efficient harvesting of energy in next-generation displays and light sources, and underlie the most advanced organic light-emitting diodes (OLEDs) in use today. The global OLED market reached $38.4B USD in 2021, and is expected to nearly double in the next five years as TADF technology enables cellphones, televisions, and light fixtures with more vibrant colours, longer battery lives and higher contrast. This paradigm shift led us to the question that now motivates much of our research program: Can TADF materials be used to create similarly disruptive technologies in other fields where fluorescent materials are used? This proposal aims to apply TADF technology to three key areas of fluorescent materials research. First, we will develop luminescent nanoparticles for fluorescent imaging and tracking of diseased cells. Using TADF, we will develop probes that filter out the fluorescent background signal from biological cells and tissues, giving higher-resolution images of cells and cell structures. Second, we will use TADF materials as photocatalysts, allowing us to accelerate chemical reactions using light. Unlike conventional fluorescent materials, a TADF material can store the energy from light in its electrons for longer, giving it time to pass that energy on to other molecules. In this way, the TADF material acts as a photocatalyst, and can be used to synthesize polymers, pharmaceuticals, or other advanced materials that are difficult to access by traditional means. Finally, we will investigate emerging applications of TADF materials in organic long-persistent luminescent (OLPL) and triplet-triplet annihilation upconversion (TTA-UC) materials. OLPL materials store energy and emit light over minutes to hours, and may offer a replacement to conventional inorganic glow-in-the-dark compounds that require rare earth elements and high fabrication temperatures. TTA-UC materials can convert low-energy absorbed light into high-energy fluorescence, ideal for biological applications where red absorbed light can be used to penetrate tissues, and blue emitted light can be used for therapy. Overall, this proposal aims to unlock the potential of TADF materials in applications beyond OLEDs, creating disruptive technologies from light-emitting materials.