AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications

Silver antimony selenide (AgSbSe2) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb2S3), silver selenide (Ag2Se), selenium (Se) and silver (Ag). Sb2S3 thin film was prepared from a chemical bath containing SbCl3 and Na2S2O3, Ag2Se from a solution containing AgNO3 and Na2SeSO3 and Se thin films from an acidified solution of Na2SeSO3, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10-3 Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe2 or AgSb(S,Se)2 depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe2/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed Voc = 435 mV and Jsc = 0.08 mA/cm2 under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe2 as an absorber material by a non-toxic selenization process is achieved.