Semiconducting AgSbSe₂thin film and its application in a photovoltaic structure

Thin films of AgSbSe2 have been prepared by heating a Sb2S3–Ag stack, with the Ag side in contact with a chemically deposited Se thin film, which served as a planar source of Se vapour. A two-stage process, consisting of the formation of an Ag2Se film through the reaction of a vacuum deposited Ag film in the Se vapour at about 80 °C, and its reaction at 300 °C with a chemically deposited Sb2S3 film, results in the formation of the AgSbSe2 film. X-ray diffraction studies illustrate the structural evolution in the formation of this film. The material possesses an indirect optical band gap of about 0.9 eV. Thermoelectric measurements on the films showed a Seebeck coefficient of 500 µV K−1 (p-type), and thus a hole concentration of ~1022 m−3. The feasibility of application of these films as a photovoltaic absorber material is illustrated for the structure SnO2–CdS–(i)Sb2S3–(p)AgSbSe2, in which an open circuit voltage of 530 mV has been observed under an intensity of illumination of 2 kW m−2 using a tungsten–halogen lamp.