Optical Properties of p-Bi₂S₃:Sn²⁺ and n-Bi₂S₃:Sn⁴⁺ Films and Photovoltaic Properties of Their Heterostructures

Abstract

The p-Bi₂S₃:Sn²⁺ and n-Bi₂S₃:Sn⁴⁺ films and their heterojunction films with uniform and dense microstructures were deposited on indium tin oxide (ITO) glass substrate by a chemical bath deposition. The n-Bi₂S₃:Sn⁴⁺ and p-Bi₂S₃:Sn²⁺ films had average particle sizes of ~5–25 nm and ~1–4 nm, and optical band gaps of ~1.36–1.59 eV and ~1.61–1.80 eV, respectively. The short-circuit current density, open-circuit voltage, and efficiency of the ITO/p-Bi₂S₃:Sn²⁺/n-Bi₂S₃:Sn⁴⁺/Pt film photovoltaic cells increased with the increase in their thicknesses. The cell with maximal thickness of ~630 nm had short-circuit current density of ~6.5 mA/cm², open-circuit voltage of ~2.41 V, and photovoltaic efficiency of ~10.31% under irradiation of visible light with intensity of 100 mW/cm².