Patent ID: 8779283

Claim:
A method of making a solar cell, comprising: applying heat to a metal alloy and a source material comprising selenium, or sulfur, or a combination thereof, wherein applying the heat comprises: annealing the metal alloy with the heat to redistribute materials in the metal alloy to generate multiple layers, wherein the multiple layers include a surface layer and a back contact layer and wherein the surface layer is on a first side of the back contact layer; at least partially vaporizing the source material using the heat to form vapors of selenium, or sulfur, or a combination thereof; and contacting the metal alloy with the vapors of selenium, or sulfur, or a combination thereof, to selenize or sulfurize at least the surface layer of the metal alloy; and wherein the back contact layer of the multiple layers is the back contact layer without any additional substrate on a second side of the back contact layer opposite the first side.