Copper sulfides obtained by spray pyrolysis — Possible absorbers in solid-state solar cells

Copper sulfide (Cu x S, x= 1.8-2) thin films were deposited at 285 °C by spray pyrolysis from aqueous and alcoholic solutions of copper (II) chloride and thiourea with different Cu:S molar ratio. The XRD analysis showed that deposited films are chemically close to chalcocite (Cu 2 S) or to mixtures of copper-rich phases (Cu 2 S, Cu 1.8 S, Cu 1.9375 S) in which chalcocite or digenite (Cu 1.8 S) is predominant. The films containing the single phase Cu 2 S are denser and more homogenous than the films formed by two or more phases. The current-voltage (I-V) dark curves showed the diode behavior of the films, depending on the film thickness.