Patent ID: 8906732

Claim:
A method for fabricating a thin film photovoltaic device, the method comprising: providing a plurality of substrates, each of the substrates having a surface region, an overlying first electrode material, and a photovoltaic absorber material; providing a chemical bath comprising an including a zinc salt species, an ammonia species, an organosulfur species, and a sodium hydroxide species, wherein the aqueous solution is dynamically maintained at a pH of between about 11 and about 12; immersing the plurality of substrates in the chemical bath; maintaining the chemical bath at a temperature ranging from about 70 to about 80 degrees Celsius during at least the immersing of the plurality of substrates; while the substrates are immersed, forming a buffer layer including at least a zinc-oxygen-sulfide compound free of cadmium with a thickness ranging from 10 nm to 30 nm overlying the photovoltaic absorber material; removing the plurality of substrates having at least the photovoltaic absorber material and the buffer material from the chemical bath; and subjecting the plurality of substrates to a cleaning solution followed by a drying process.