| dc.description.abstract | Since their first report in the 1800s, conjugated polymers have gained significant attention for their ability to exhibit the optical and electronic properties of inorganic semiconductors and the physical traits of organic plastics. This has led to the development of organic electronics with notable commercial applications, such as organic photovoltaics and organic light-emitting diodes. The tunability of these materials has also allowed for the production of materials that absorb and emit near-infrared (NIR) light, making them useful for NIR photodetection and bioimaging.
NIR photodetection is important for several applications, including optical communication, artificial vision, and health monitoring. Commercially available NIR photodetectors use inorganic materials such as InGaAs and HgCdTe, which are toxic, inflexible, and have limited tunability of their spectral response range. Conjugated polymers offer an alternative to these materials as they are considerably less toxic, flexible, and their spectral response range is tunable through molecular design. Thieno[3,4-b]pyrazine (TP) homopolymers show potential for NIR photodetectors due to their ability to absorb NIR light. However, TP homopolymers generally exhibit low solubility, which limits their application to devices. To improve solubility, TP homopolymers were functionalized with branched side chains, resulting in soluble materials with bandgaps as low as 0.64 eV. In addition, NIR photodetectors made from these materials exhibit specific detectivity values that are competitive with some of the top-performing polymers currently used in NIR photodetectors. Moreover, TP homopolymers are of relatively low synthetic complexity compared to current state-of-the-art conjugated polymers. The overall design, synthesis, characterization, and device data for these materials will be presented.
Both absorption and emission are crucial for bioimaging, unlike NIR photodetection which only requires absorption. Fluorescence imaging allows for fast feedback and high sensitivity while being relatively inexpensive compared to traditional imaging methods. The NIR-I and NIR-II windows (700–900 and 1000–1700 nm, respectively) are ideal for fluorescence imaging due to the reduced absorption, autofluorescence, and scattering in these regions. Organic small molecule fluorophores have gained interest due to their low toxicity, fast excretion rates, tunability, and good biocompatibility. The overall design, synthesis, and characterization of several small molecule emitters will be presented. | en_US |
