Patent ID: 8383450

Claim:
A method for forming a thin film photovoltaic material, the method comprising: providing a plurality of substrates, each of the substrates having a surface region, an overlying first electrode material, an absorber material including at least a copper species, an indium species, and a selenium species; providing a chemical bath comprising an aqueous solution including a cadmium species, an ammonia species, and an organosulfur species, wherein the chemical bath is maintained at a pH of between about 11 and about 12; immersing the plurality of substrates in the chemical bath; maintaining the aqueous solution at a temperature ranging from about 50 to about 60 degrees Celsius during at least the immersing of the plurality of substrates; while the substrates are immersed, forming a window material including at least cadmium sulfide to a thickness of about 200 Angstroms and less; removing the plurality of substrates having at least the absorber material and the window layer from the aqueous solution; subjecting the aqueous solution to a filter process to substantially remove particles greater than about 5 microns, the particles including colloids of cadmium sulfide; and subjecting the plurality of substrates to a cleaning solution.