Multifunctional Sensors Based on Doped Indium Oxide Nanocrystals

There is an increasing need for multifunctional sensors that can detect radiation, biological activity, gas, etc. for efficient health monitoring, neurological medical devices, and human–machine interfaces in recent years. Herein, we demonstrated a multifunctional Sn-doped In 2 O 3 nanocrystal (ITO NC) based device for ulyoutraviolet (UV)/infrared (IR) dual-band photodetection and light-activated efficient nitrogen dioxide (NO 2 ) gas sensing at room temperature (RT). The effects of different surface ligands and annealing process of ITO NCs on their photodetection performance were investigated. The ITO NCs capped with 1,2-ethanedithiol (EDT) show a responsivity of 31.3/177.7 mA W –1 and normalized detectivity of ∼1 × 10 10 /10 9 cm Hz 1/2 W –1 under UV/IR illumination at 375/2200 nm at RT. The potential of the ITO NCs sensors to monitor low concentrations of NO 2 is activated by light illumination. The sensor has a higher response (4.2) to 1 ppm of NO 2, shorter response/recovery time (156.8/554.2 s), and a lower detection limit (LOD) (219 ppb) under UV illumination compared within a dark environment. The LOD of the sensor is lower than the allowable exposure limit of NO 2 specified in “Air Pollutant Limits” of the Occupational Safety and Health Administration (OSHA). Our work paves an alternative platform for the development of low-cost, integration-friendly multifunctional devices.