Thin films of antimony sulfide have been deposited from chemical baths containing antimony trichloride and sodium thiosulfate maintained at 10°C. Upon annealing in nitrogen at 300°C for 1 h, the films become photosensitive with photo-to dark-current ratio of two to three orders of magnitude at 2 kW m2 tungsten halogen radiation. The annealed films are crystalline with an X-ray diffraction pattern matching that of stibnite, 5b753, (JCPDS 6-0474) and show an optical bandgap of 1.78 eV. Deposition of a thin film of CuS on the antimony sulfide thin film and subsequent annealing in nitrogen at 250°C for 1 h produces films with acceptable solar control characteristics: integrated visible transmittance, 15%; integrated visible reflectance, 12%; integrated infrared transmittance, Tir, 14%; integrated infrared reflectance, R1,, 36%; and a shading coefficient of about 0.35. The X-ray diffraction patterns of the annealed 5b757-CuS thin films indicate the formation of a ternary compound with the structure of famatinite, Cu35b54.

Polycrystalline thin films ( 100–450nm in thickness) of SnS formed from chemical baths of Sn(II) in acetic acid/ HCl solution, triethanolamine, NH3 (aq), and thioacetamide are polymorphic consisting of zinc blende (ZB) and orthorhombic (OR) structures. The ZB structure for the SnS film, reported in this work for the first time, has a lattice constant a=0.579nm and a direct (forbidden) bandgap of 1.7eV , which is distinct from that of SnS(ZB) , about 1eV . The electrical conductivity of SnS(ZB) is 6×10−6 (Ωcm)−1 p-type, with activation energies for the conductivity of 0.5eV at room temperature and 1.6meV near 10K . When a SnS(ZB) film is heated in air at 500°C for 30min , part of it transforms to SnO2 and to SnS(OR) ; after 2h 30min at 550°C in air the film converts to transparent SnO2 . Such a film has a bandgap of 3.7eV and electrical conductivity, ∼1 (Ωcm)−1 . Photovoltaic effect in different structures involving these films is presented.

Thin films of copper sulphide with thickness up to 0.5 µm were deposited at 70 • C on glass substrates from a solution containing copper(II) chloride, sodium thiosulphate and dimethylthiourea. As prepared and after annealing at 200 • C in N 2 (100 millitorr), these films showed x-ray diffraction patterns matching that of the mineral covellite (CuS). Annealing the films for 1 h each at 300 • C and 400 • C in nitrogen resulted in their conversion to Cu 1.8 S (digenite) and Cu 1.96 S (chalcocite), respectively. The reduction in sulphur content of the films is evident in the x-ray florescence spectra. The sheet resistance of the films varied with annealing temperature. For a film of 0.5 µm thickness, the observed sheet resistance values are: 180 / (as prepared), 6 / (200 • C), 17 / (300 • C) and 30 / (400 • C). The low sheet resistance (and thus the high conductivity, 10 3 −1 cm −1 ) leads to a high near-infrared reflectance for the films, 65% (CuS) and 40% (Cu 1.96 S), at a wavelength of 2500 nm. Analyses of the optical band gap of the films indicate an indirect gap of 1.55 eV for CuS and Cu 1.8 S and 1.4 eV for Cu 1.96 S.

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The tin sulfide solar cell has acquired prominence in recent years. We present the characteristics of two polymorphs of SnS and their perspectives in thin‐film solar cells. Thin‐film SnS with cubic crystalline structure (SnS‐CUB) was obtained via two chemical routes. This semiconductor is distinct from the more common SnS thin films of orthorhombic crystalline structure (SnS‐ORT), also obtained by chemical routes. The SnS‐CUB reported here with a lattice constant a of 11.587 Å replaces the zinc blende structure previously reported for this material with a of 5.783 Å. Thin films of SnS‐CUB have an optical bandgap (Eg) of 1.66–1.72 eV and electrical conductivity (σ) of 10−6 Ω−1 cm−1. These characteristics distinguish them from SnS‐ORT presented here with an Eg of 1.1 eV and σ typically higher by two orders of magnitude. We discuss the uncertainties that have prevailed in the assignment of crystalline structure for SnS‐CUB and SnS‐ORT. The optical and electrical properties of these two polymorphs of SnS are contrasted in the context of light‐generated current density in solar cells. We conclude that the two SnS polymorphs when considered together as optical absorbers offer wider prospects for tin sulfide thin‐film solar cells.

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A chemical deposition technique, much simpler and more versatile than previously reported and capable of yielding good quality SnS films of thickness up to 1 1 . 2 p under a choice of deposition conditions, is presented. The as-prepared films are polycrystalline with p-type dark conductivity in the range 10 -5-1 0 -4 Q -1 cm-' for the thicker ( -1 pm) films and showing a photocurrent to