Mobility of Long-Lived Fullerene Radical in Solid State and Nonlinear Temperature Dependence

A singly bonded fullerene dimer [C60R]2 in
the solid state thermally generates a pair of fullerene radicals C60R• that dissociate reversibly and irreversibly
upon heating and cooling of the solid. The temperature dependence
of the electron mobility of the solid shows striking nonlinearity,
caused by the dissociation of a strongly interacting radical pair
into two free radicals, which interact with the neighboring fullerene
molecules to increase the mobility 10 times to a value of 1.5 ×
10–3 cm2 V–1 s–1. The nonlinearity is due to the plastic crystalline
nature of fullerene crystals.