Ultrasensitive ambient-stable SnSe₂-based broadband photodetectors for room-temperature IR/THz energy conversion and imaging

The advent of tin diselenide (SnSe2) enables novel pathways for optoelectronics, due to its reduced cost, ultralow thermal conductivity and high potential for thermoelectricity. To date, SnSe2-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 SnSe2 photodetectors with exfoliated SnSe2 nanosheets extended in the range of THz frequency, exhibiting high responsivity (170 V W-1), fast speed (2.2 μs), as well as room-temperature operation, based on efficient production of hotelectrons under deep-subwavelength electromagnetic focus, which outperform thermal-based photodetectors. Our SnSe2-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 SnSe2 crystals, validated by surface-science experiments. Our results demonstrate the suitability of SnSe2for multispectral sensing and real-time imaging.