Low-cost and Earth-abundant Solar Cells from Nanoparticles

Solar energy has the greatest capability to supply clean renewable energy but is not fully utilized because of the high cost associated with solar cell fabrication. The costs have decreased in recent years with the advancement of thin-film technologies, but these systems rely on rare elements such as tellurium and indium, where the elements global supply cannot satisfy the global power requirements.

Copper-zinc-tin-sulfide (Cu2ZnSnS4 hereafter CZTS) is one earth abundant thin-film semiconductor material that has the potential to fully satisfy the global energy need in an economic matter. Currently CZTS has been fabricated by utilizing various vacuum, electrochemical, and liquid deposition based techniques, yielding power efficiencies up to 6.7% and derivatives of CZTS with selenium incorporation (CZTSSe) have yielded 9.7%. Difficulties presented by their work include scalability, compositional uniformity, and the use of highly toxic hydrazine.

The work presented addresses these issues through utilizing CZTS nanoparticles. The CZTS nanoparticles were formed and then sintered in a selenium environment to form dense CZTSSe films resulting in a final efficiency of 7.2%, which is the second highest efficiency reported in the literature for this material. This process is scalable, uniform, and does not necessitate the use of toxic solvents.