Patent ID: 8518737

Claim:
A method for forming a metal layer on a solar cell substrate comprising the steps of: providing a reaction chamber comprising an anion-selective electrode in communication with a solution comprising an ammonium ion, a metal ion, and a buffer, adjusting the pH of the solution to a slightly basic pH; monitoring a metal ion concentration in the solution with the anion-selective electrode; forming a metal-ammonium complex in the reaction chamber from the ammonium ion and the metal ion; decomplexing the metal-ammonium complex to form a decomplexed metal ion; detecting a decrease in the metal ions concentration and reducing the pH to a neutral pH; titrating the decomplexed metal ion with a thiourea composition to form a metal-thiourea complex; forming a metal sulfide composition from the metal-thiourea complex; and depositing the metal sulfide composition on a solar cell substrate in the reaction chamber to form a metal sulfide layer.