| Summary: | Over the last few decades, it has become evident that current energy production for humanity since the industrial revolution has incurred the emission of greenhouse gases (GHGs) into the Earth’s atmosphere, resulting in rampant pollution, global warming, ocean acidification and other disastrous environmental effects. The continued emission GHGs is a direct result of the predominant use of fossil fuels to meet an exponentially increasing global energy demand. Development of sustainable energy technologies is a global imperative to avoid future catastrophe. Photovoltaics (PV) are an ideal resource that allows us to convert our greatest supply of energy, sunlight, directly into our greatest source of energy consumption, electricity. In the last four decades, PV research for new solar materials and fabrication methods to compete with crystalline silicon (c-Si) modules has expanded in an effort to reach $1/Watt solar energy. Thin films of chalcogenide semiconductors such as CdTe, Cu(In,Ga)(S,Se)2 and Cu2ZnSn(S,Se)4 (CZTSSe) have ideal band gaps for solar absorption, require 100 times less material than c-Si, and do not require high levels of purity, thus lowering material costs and processing. The lower material cost from earth-abundant elements and ability to solution process CZTSSe make this material an ideal competitor with current PV technologies. Solution based methods, such as roll to roll printing of nanoparticle inks, are a more scalable method to deposit the absorber film. Once coated, only the selenization sinters sulfide nanoparticles into micron sized grains, which are required for high efficiency PV devices. Selenization and sulfurization equipment were engineered to study the chalcogenization of CZTS and CZTSe nanoparticle films. Due to the volatility of sulfur, liquid assisted sintering does not occur. However, abnormal grain growth above 550°C may occur as the kinetics of nanoparticle thermolysis become appreciable, thus forming nuclei at the film surface. Recent literature has shown the necessity of ...
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