Hierarchial Junction Solar Cells Based on Hyper-Branched Semiconductor Nanocrystals

Abstract : In the first phase, hyperbranched nanocrystals of Cadmium Selenide [CdSe] were synthesized, isolated, and characterized. During active research on CdSe nanostructure-based solar cells, toxicity and processing complexity issues were encountered. The research was redirected to find non-toxic and abundant materials. It was determined that copper (I) sulfide and iron disulfide pyrite generated a much broader impact for photovoltaic solar cell applications. First, a simple low temperature solution phase synthesis of copper (I) sulfide nanocrystals was demonstrated. An all-inorganic bilayered solar cell device based on these nanocrystals and CdS nanorods demonstrated power efficiencies of about 1.6%. Second a novel single source precursor approach was established to synthesize pure phase iron disulfide pyrite nanocrystals with high purity through a surfactant-assisted hydrothermal reaction. These nanocrystals represent new groups of well-defined nanoscale structures for high-performance photovoltaic solar cells based on non-toxic and earth abundant materials.