Development of New Organic Electronic and Optoelectronic Materials

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Luminescent materials have important applications in sensing, bioimaging, theranostics, and light-emitting technologies. Development of functional fluorophores is at the heart of these cutting-edge research fields. Built upon our previous studies, we propose to investigate new organic luminescent materials based on innovative molecular design and synthesis. The first class of materials are called AIE-active interpenetrating network (IPN) hydrogels. AIE stands for "aggregation-induced emission". An AIE fluorophore is non-emissive when molecularly dissolved, but highly emissive upon aggregation. IPN hydrogels are blends of two or more hydrogel polymers interlaced with one another, which show significant advantages in terms of mechanical stability, high adsorbent performance, and sensitive responsiveness to external stimuli. In our studies, we will synthesize various AIE fluorophores chemically bonded to the frameworks of IPN hydrogels. The AIE fluorophores act as "nodes" to cross-link with the hydrogel networks, and are expected to display versatile fluorescence properties in response to various external stimuli. The proposed AIE-active IPN hydrogels will be developed into "intelligent" fluorescent materials for environmental sensing, bioimaging, and other fluorescence applications. The second class of fluorophores to be investigated are called TADF fluorophores. TADF refers to "thermally activated delayed fluorescence". TADF fluorophores have attracted enormous attention in recent years owing to their unique advantages of long-lived delayed fluorescence and high internal quantum efficiency. TADF materials have been popularly explored as next-generation emitters for organic light-emitting devices (OLEDs), as well as bioimaging and photocatalysis. Our proposed research will target pyrene-based purely organic fluorophores, which will be synthesized, characterized and then optimized for light-emitting and fluorescence imaging applications. Apart from various new flurophores, we will also investigate an unprecedented class of functionalized "carbon nanobelts" (CNBs). CNBs possess fascinating molecular structures and electronic properties, akin to their larger analogues - carbon nanotubes. CNBs were conceptually proposed as early as 1954, but have only been successfully synthesized in the past three years. To contribute to this challenging but quickly growing field, we propose to construct a new type of functionalized CNBs, using bromine-substituted quinodimethane (QMD) as a key building component. Our synthetic strategy is to connect two curved QMD-embedded nanostrips to form a belt via efficient cycloaddition reactions. A key advantage of such CNBs is that various redox-active functional groups can be readily installed on their edges to bring about redox controllability and supramolecular self-assembling properties. Fundamental properties and applications of the CNBs and related nanocarbon materials will be explored in our studies.