Ultrasensitive ambient-stable SnSe ₂ -based broadband photodetectors for room-temperature IR/THz energy conversion and imaging

Abstract

Abstract The advent of tin diselenide (SnSe 2 ) enables novel pathways for optoelectronics, due to its reduced cost, ultralow thermal conductivity and high potential for thermoelectricity. To date, SnSe 2 -based optoelectronic devices have been focused on the visible and infrared range of the electromagnetic spectrum, with efficiency sharply decreasing at longer wavelength. Here, we present SnSe 2 photodetectors with exfoliated SnSe 2 nanosheets extended in the range of THz frequency, exhibiting high responsivity (170 V W −1 ), fast speed (2.2 μ s), as well as room-temperature operation, based on efficient production of hotelectrons under deep-subwavelength electromagnetic focus, which outperform thermal-based photodetectors. Our SnSe 2 -based detectors show high-contrast imaging from terahertz (THz) up to visible. The outstanding ambient stability of our broadband photodetectors in a timescale of months is due to the chemical inertness of stoichiometric SnSe 2 crystals, validated by surface-science experiments. Our results demonstrate the suitability of SnSe 2 for multispectral sensing and real-time imaging.