Technique for Achieving Large-Grain Ag2ZnSn(S,Se)4 Thin Films

A method of forming a solar cell, comprising:

• contacting a conducting substrate with an Ag source, a Zn source, a Sn source, and at least one of an S source and an Se source under conditions sufficient to form the absorber film on the conducting substrate having a target composition of:
• AgXZnYSn(S,Se)Z, wherein 1.7<x<2.2, 0.9<y<1.3, and 3.5<z<4.5, and including an amount of the Ag source that is from about 10% to about 30% greater than is needed to achieve the target composition;
• annealing the absorber film;
• removing excess Ag, if any, from the absorber film;
• forming a buffer layer on the absorber layer;
• and
• forming a transparent front contact on the buffer layer.

A solar cell, comprising:

• a substrate;
• a conductive layer on the substrate;
• an absorber layer on the conductive layer, the absorber layer having a composition of:
• AgXZnYSn(S,Se)Z, wherein 1.7<x<2.2, 0.9<y<1.3, and 3.5<z<4.5, and wherein the absorber layer has an average grain size of from about 0.5 micrometers to about 4 micrometers, and ranges therebetween;
• a buffer layer on the absorber layer;
• and
• a transparent front contact on the buffer layer.