Antimony sulfide thin films in chemically deposited thin film photovoltaic cells

Antimony sulfide thin films of thickness ≈ 500 nm have been deposited on glass slides from chemical baths constituted with SbCl3 and sodium thiosulfate. Smooth specularly reflective thin films are obtained at deposition temperatures from − 3 to 10 °C. The differences in the film thickness and improvement in the crystallinity and photoconductivity upon annealing the film in nitrogen are presented. These films can be partially converted into a solid solution of the type Sb2SxSe3 − x, detected in X-ray diffraction, through heating them in contact with a chemically deposited selenium thin film. This would decrease the optical band gap of the film from ≈ 1.7 eV (Sb2S3) to ≈ 1.3 eV for the films heated at 300 °C. Similarly, heating at 300 °C of sequentially deposited thin film layers of Sb2S3–Ag2Se, the latter also from a chemical bath at 10 °C results in the formation of AgSb(S/Se)2 with an optical gap of ≈ 1.2 eV. All these thin films have been integrated into photovoltaic structures using a CdS window layer deposited on 3 mm glass sheets with a SnO2:F coating (TEC-15, Pilkington). Characteristics obtained in these cells under an illumination of 850 W/m2 (tungsten halogen) are as follows: SnO2:F–CdS–Sb2S3–Ag(paint) with open circuit voltage (Voc) 470 mV and short circuit current density (Jsc) 0.02 mA/cm2; SnO2:F–CdS–Sb2S3–CuS–Ag(paint), Voc ≈ 460 mV and Jsc ≈ 0.4 mA/cm2; SnO2:F–CdS–Sb2SxSe3 − x–Ag(paint), Voc ≈ 670 mV and Jsc ≈ 0.05 mA/cm2; SnO2:F–CdS–Sb2S3–AgSb(S/Se)2–Ag(paint), Voc ≈ 450 mV and Jsc ≈ 1.4 mA/cm2. We consider that the materials and the deposition techniques reported here are promising toward developing ‘all-chemically deposited solar cell technologies.’