High-detectivity near-infrared photodetector based on Ag2S nanocrystals

Infrared detection is a key point in optoelectronic systems and thus has attracted considerable attention in recent years. In this paper, a novel, heavy metal-free, and low-cost near-infrared photoconductor based on Ag2S nanocrystals (NCs) was realized for the first time. Ag2S NCs were synthesized by a facile chemical synthesis method at room temperature and were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and optical absorption. The photoconductor was fabricated by drop-casting Ag2S NCs on the interdigitated electrodes which were designed on a printed circuit board. The fabricated photodetector was able to work with a very low bias voltage of 0.05 V. Device performance was evaluated in terms of photosensitivity, responsivity, and detectivity under 750, 850, and 940 nm wavelengths illuminations. The fabricated photodetector exhibited a high detectivity of 2.7×1010 (more than 109 Jones) under 750 nm wavelength illumination at room temperature. [Display omitted] •A facile room-temperature synthesis was used to produce Ag2S nanocrystals in the range of 30–40 nm.•A photoconductor based on Ag2S nanocrystals has been realized for the first time.•Fabricated photodetector has shown a high detectivity under near-infrared illumination with a very low voltage bias.