(153b) Synthesis Routes of Phosphorous-Free Semiconducting Selenide Nanoparticles for Photovoltaic Applications

Selenium based semiconductors have filled large roles in photovoltaics with materials that include Copper-Indium-Gallium-Selenide (CIGSe), Cadmium Selenide, Copper Selenide, and Copper-Zinc-Tin-Selenide (CZTSe).  These materials, and their other chalcogenide derivatives, are major players in thin-film photovoltaics for lower cost solar cells.  Nanomaterials of these devices have been fabricated, but traditionally rely on either toxic selenium sources, or elemental selenium dissolved with phosphorous or boron containing chemicals.  The hazards of toxic selenium sources should be avoided for use in scalable solar cell manufacturing.  Meanwhile the addition of phosphorous and boron should be avoided in order to keep these components from contaminating the final device fabricated from these nanocrystals.

We have developed a method to enable the fabrication of selenide nanocrystals from elemental selenium without using any phosphorous or boron in the process. This process has allowed the formation of selenide nanocrystals in organic media with great size control, and for applications in scalable roll-to-roll device fabrication.  By adjusting the S to Se ratio, band-gap control of the individual nanocrystals is also achieved.  These nanocrystals are currently being investigated for their photovoltaic applications.