Ultrasensitive thin film infrared sensors enabled by hybrid nanomaterials

Abstract

IR sensing is an important technology with applications in renewable energy, environmental science and medical engineering. Herein environment-friendly IR sensors based on the single-walled carbon nanotube–copper sulfide nanoparticle (SWNT–CuS NP) hybrid nanomaterials are reported. The IR response in the photocurrent of a SWNT–CuS NP hybrid thin-film sensor is significantly enhanced when the IR light illuminates the thin-film device asymmetrically. We show that the change of photocurrent is up to 300%, which is 10× to 100× larger than those of other reported nanomaterial-based IR sensors. The detection limit can be as low as 48 μW mm⁻², among the lowest of the previously reported IR nanosensors. The dramatically enhanced sensitivity and detection limit are due to the temperature difference between the two junctions formed by the nanohybrid thin film and Cu-wire electrodes under asymmetric IR illumination, and the difference between the effective Seebeck coefficient of the nanohybrid thin film and that of the Cu wire. The IR sensor embedded in polydimethylsiloxane (PDMS) layers has been fabricated and tested, indicating its potential application as a flexible IR sensor.