Techniques for enhancing performance of photovoltaic devices

A method of fabricating a photovoltaic device, comprising the steps of:

• providing a substrate;
• and
• forming an Sb-doped absorber layer formed on the substrate represented by a formula,
• Cu1-yIn1-xGaxSbzSe2-wSw,
• wherein:
• 0≦x≦1, and ranges therebetween;
• 0≦y≦0.2, and ranges therebetween;
• 0.001≦z≦0.02, and ranges therebetween;
• 0≦w≦2, and ranges therebetween,
• wherein an amount of Sb in the absorber layer is from about 0.1 atomic percent to about 2 atomic percent of that of a sum of the In and the Ga,
• and wherein the absorber layer has a grain size of from about 0.2 μm to about two μm measured as a longest length of a grain from a cross-section of the absorber layer, and wherein the longest length of the grain from the cross-section of the film is greater than or equal to a thickness of the film;
• and
• performing a final anneal of the absorber layer at a temperature of from about 350° C. to about 375° C.,
• wherein the step of forming the Sb-doped absorber layer further comprises the steps of:
• preparing an Sb-doped absorber layer precursor solution;
• spin-coating the Sb-doped absorber layer precursor solution onto the substrate;
• annealing the Sb-doped absorber precursor layer coated on the substrate, wherein the annealing step comprises an intermediate anneal that is configured to decompose the Sb-doped absorber precursor layer coated on the substrate;
• and
• repeating the spin-coating and annealing steps until a desired thickness for the Sb-doped absorber layer is achieved, wherein the spin-coating and annealing steps are all performed in-situ in a same inert atmosphere, in a same nitrogen-filled drybox,
• and wherein the step of preparing the Sb-doped absorber layer precursor solution, further comprises the step of:
• dissolving a Cu source, an In source, a Ga source, an Se source and an Sb source in hydrazine to produce one or more component solutions, wherein the Sb source is antimony trisulfide;
• and
• mixing two or more of the component solutions to form the Sb-doped absorber layer precursor solution.