Luis Echegoyen

Abstract:

Carbon-based chemical compounds and materials are relatively inexpensive and very effective as selective Electron Transporting Layers (ETLs) in solar cells. Our work in this area has been primarily with buckminsterfullerene compounds, also called “buckyballs” or simply fullerenes, which are pure-carbon cages that are excellent electron acceptors and 3D transporters. We have functionalized fullerenes in order to modulate and probe their specific interfacial interactions in perovskite solar cells to understand the details and to enhance the cell performance efficiencies. Pyridine-functionalized fullerenes were tested as ETLs, both as pure compounds as well as in combination with other ETL compounds in order to discriminate their ability to extract electrons at the perovskite interface and to transport the electrons through the bulk phase. Results clearly showed that the pyridine-functionalized compounds act as efficient electron extractors at the interface but are not good electron transporters as a bulk phase.
In addition to regular fullerenes we have also worked with endohedral versions, which are carbon cages which encapsulate ions and/or atoms and clusters inside, stabilized by electronic interactions with the cages. These nano-sized compounds, which we also call “Buckyball Maracas” due to their composition and structure, were recently shown to act as reasonably efficient non-precious metal-containing molecular catalysts to effect the Hydrogen Evolution Reaction (HER), or water splitting, to produce hydrogen gas. We initiated this work and are currently exploring the fundamental aspects of the HER with other endohedral fullerene compounds, both to understand the details and to increase their efficiencies.