Lithium Cation Endohedral Fullerene

A new solution to highly efficient solar cells

Li⁺@C₆₀ provides long lasting separation of electron charge. Li⁺@C₆₀^-sulphonated porphyrin supramolecular nanoclusters support increased photoelectricalchemical performance of photovoltaic cells. Photoelectrochemical solar cells composed of supramolecular nanoclusters of lithium encapsulated fullerene and zinc sulfonated meso-tetraphenylporphyrin exhibit significant performance enhancement as compared with the reference system containing only a single component.

References

1. Ohkubo, Y. Kawashima and S. Fukuzumi, "Strong supramolecular binding of Li⁺@C₆₀ with sulfonated meso-tetraphenylporphyrins and long-lived photoinduced charge separation", Chem. Commun., 48, 4314-6 (2012)
2. Ohkubo, Y. Kawashima, H. Sakai, T. Hasobe and S. Fukuzumi, "Enhanced photoelectrochemical performance of composite photovoltaic cells of Lii⁺@C₆₀^- sulphonated porphyrin supramolecular nanoclusters ", Chem. Commun., 49, 4474-6 (2013)

Li+ ion is encapsulated inside C₆₀ (Fullerene).

Li⁺@C₆₀ reacts with various anions and forms salts (e.g. SbCl₆^- and PF₆^-), which are useful in switch and sensor applications. This property can be utilized for sensors and switches.

References

1. Aoyagi, E. Nishibori, H. Sawa, K. Sugimoto, et al., "A layered ionic crystal of polar Li@C₆₀ superatoms", Nature Chemistry, 2, 678-83 (2010).
2. Aoyagi, Y. Sado, E. Nishibori, et al., "Rock-Salt-Type Crystal of Thermally Contracted C₆₀ with Encapsulated Lithium Cation", Angew. Chem. Int. Ed., 51, 3377-81 (2012).

Higher ion mobility in organic solvent

Li⁺@C₆₀^- is produced in the reaction above, and is electrically neutral. Because Li⁺@C₆₀·PF₆^- shows higher mobility inside organic solvents than n-Bu₄N⁺·PF₆^-, which is widely used as electrolyte, many electro-chemical applications of Li⁺@C₆₀ are envisaged. In fact, Li⁺@C₆₀^·-, a radical anion, is selectively produced when Li⁺@C₆₀^-·PF₆^- is reduced.

References

1. Ueno, K. Kokubo, Y. Nakamura, K. Ohikubo, et al., "Ionic conductivity of [Li⁺@C₆₀](PF₆^-) in organic solvents and its electrochemical reduction to Lii⁺@C₆₀^·-", Chem. Commun., 49, 7376-8 (2013).