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 Sb 2 S x Se 3-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 (Sb 2 S 3 ) to ≈1.3 eV for the films heated at 300 °C. Similarly, heating at 300 °C of sequentially deposited thin film layers of Sb 2 S 3 -Ag 2 Se, 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 SnO 2 :F coating (TEC-15, Pilkington). Characteristics obtained in these cells under an illumination of 850 W/m 2 (tungsten halogen) are as follows: SnO 2 :F-CdS-Sb 2 S 3 -Ag(paint) with open circuit voltage (V oc ) 470 mV and short circuit current density (J sc ) 0.02 mA/cm 2 ; SnO 2 :F-CdS-Sb2S3-CuS-Ag(paint), V oc ≈ 460 mV and J sc ≈ 0.4 mA/cm 2 ; SnO 2 :F-CdS-Sb 2 S x Se 3-x -Ag(paint), V oc ≈ 670 mV and J sc ≈ 0.05 mA/cm 2 ; SnO 2 :F-CdS-Sb2S3-AgSb(S/Se)2-Ag(paint), V oc ≈ 450 mV and J sc ≈ 1.4 mA/cm 2 . We consider that the materials and the deposition techniques reported here are promising toward developing 'all-chemically deposited solar cell technologies'.