Soft Matter Infrared Photodetectors

Infrared detection in the shortwave (1000-3000 nm), midwave (3000-5000 nm) and longwave (8000-14000 nm) regions has traditionally been dominated by compound semiconductors such as indium antimonide and mercury cadmium telluride, among others. These materials must be epitaxially grown and cooled to cryogenic temperatures before use. Alternative materials such as strained layer superlattices that are thermoelectrically cooled have been developed but still have complex and costly deposition processes. We have developed a new class of infrared photoconductive detectors active between 1000-14000 nm using disordered, soft matter semiconductors: conjugated polymers. Using both solution processing and vapor phase deposition, conductive polymers with direct, shortwave infrared bandgaps or degenerately doped effective bandgaps have been incorporated into IR detectors whose performance approaches that of inorganic compound semiconductor-based devices, but at room temperature and with no optimization. We have observed several unique morphologies, ranging from solid films to intercolated wires to isolated platelets, all of which function as effective infrared detectors for blackbody radiation. An extensive study was also undertaken to understand how deposition parameters affect electronic transport properties in the photoconductive films.<br/><br/>1. J. H. Vella, A. R. Benasco, S. Nikodemski, M. I. Vakil, and J. D. Azoulay, <i>Macromol. Rapid Commun. </i><b>2023</b>, accepted.<br/>2. J. H. Vella, S. Nikodemski, A. R. Benasco, T. A. Prusnick and V. Vasilyev, <i>Synth. Met. </i><b>2023</b>, <i>293</i>, 117277.<br/>3. J. H. Vella, L. Huang, N. Eedugurala, K. S. Mayer, T. N. Ng and J. D. Azoulay, <i>Sci. Adv.</i> <b>2021</b>, <i>7</i>, eabg2418.