Room Temperature Mid-IR Detection through Localized Surface Vibrational States of SnTe Nanocrystals.

Quantum dots (QDs) are now well established as promising materials for room temperature mid-infrared (MIR) detection beyond 3 µm. Here, we have replaced commonly reported mercury based quantum dots with less toxic SnTe and PbSnTe. Inverse MIR detection at room temperature is demonstrated with planar, solution, and air-processed PbSnTe and SnTe QD devices. The detection mechanism is shown to be mediated by an interaction between MIR radiation and the vibrational stretches of adsorbed hydroxyl species. Devices are shown to possess mA/W responsivity via a reduction in conductance due to MIR irradiation and, unlike classic MIR photoconductors, are unaffected by visible wavelengths. As such, these devices offer the possibility of MIR thermal imaging that has an intrinsic solution to the blinding caused by higher energy light sources.

Photo-Electrosensitive Memristor Using Oxygen Doping in HgTe Nanocrystal Films.

Nanocrystal-based electronic devices with multiple functionalities offer one avenue toward novel passive and active electronic components. Here, we exhibit a planar and fully air-processed thin film device that demonstrates a photoinduced memristive behavior and can be used as a transistor, photodetector, or memory device. Following long-term (60 h) air exposure, unpackaged nanocrystal films develop reliable memristive characteristics in tandem with temperature, gate, and photoresponse. The on/off values of more than 50 are achieved, and the devices show long-term stability, producing repeatable metrics over days of measurement. The on/off behavior is shown to be dependent on the previous charge flow and carrier density, implying a memristive rather than switching behavior. These observations are described within a long-term trap-filling model. This work represents an advance in the integration of nanocrystal films into electronic devices, which may lead to the development of multifunctional electronic components.