PbS

Lead sulfide, with the chemical formula PbS, is an inorganic compound that occurs naturally as the mineral galena, the principal ore of lead. It is a black to gray solid that crystallizes in a cubic lattice and is relatively brittle. PbS is a narrow-gap semiconductor with a room-temperature band gap of about 0.37–0.41 eV, giving it sensitivity in the infrared region. It has a rock-salt (sodium chloride-type) crystal structure, a density of about 7.6 g/cm³, and a melting point near 1114 °C.

PbS can be obtained commercially from mining and processing of the galena ore. In the laboratory, it can be synthesized by precipitating from solutions containing a lead(II) salt and a sulfide source, or by high-temperature solid-state reactions. Nanostructured forms, including colloidal PbS quantum dots, are produced by colloidal synthesis and are studied for optoelectronic applications.

Applications of PbS arise primarily from its infrared activity and semiconducting properties. It is used in infrared detectors and photoconductive devices, especially in early and some modern concepts for night-vision and sensing technologies. Colloidal PbS quantum dots enable IR-responsive devices and have been explored for solar cells and photodetectors in the near- and mid-infrared. PbS continues to be investigated for various energy and optoelectronic applications due to its tunable band gap in the infrared range.

Safety and handling considerations are important because PbS contains lead, a toxic heavy metal. Exposure should be minimized, and waste should be managed according to applicable regulations to prevent environmental contamination.