A Colloidal Quantum Dot Thermistor and Bolometer

Abstract

ABSTRACT Bolometric detection offers a compelling route to room‐temperature mid‐ and long‐wave infrared (MWIR/LWIR) photodetection by measuring temperature‐induced conductivity changes in a thermistor element thermally coupled to an absorber. However, conventional thermistor materials such as vanadium oxide (VO x ) and amorphous silicon (a‐Si) exhibit moderate temperature coefficient of resistance (TCR) values (−2 to −3%/K). Higher TCRs have been achieved using SiGe/Si quantum wells (∼−5%/K), yet these require costly epitaxial growth and further improvements are hindered by lattice mismatch‐induced defects. Here, we report a novel thermistor platform based on colloidal quantum dots (CQDs) that circumvents these limitations by exploiting their lattice‐mismatch‐free nature. By tuning the size and surface chemistry of lead chalcogenide CQDs, we engineer the energetic potential landscape to modulate thermal activation energy, achieving TCR values of up to −9%/K. We further integrate this CQD thermistor with a plasmonic metamaterial absorber (PMA), enabling room‐temperature wavelength‐selective photodetection across the mid‐ to long‐wave infrared (MWIR/LWIR) spectrum. The bolometer detectors exhibited LWIR response with a time constant of ∼8 ms and room‐temperature detectivity approaching 10 6 Jones at 9 µm, without using microelectromechanical systems (MEMS) technology.