Abstract

Recent studies have revealed that undoped solid C₆₀, or “buckminsterfullerite”, is a direct-gap semiconductor with a band gap of approximately 1.6-1.9 eV.^[1] Since the delocalized, quasifree electrons on the C₆₀ clusters lead to a large nonlinear polarizability of the individual cluster molecules,^[2] studies of solid C₆₀ may also reveal strong nonlinear optical properties as well. Our investigations indicate that photoexcited electrons at the band edge in C₆₀ remain localized on the bucky clusters, and diffuse via a hopping mechanism which consists of tunneling between these localized states. This unusual carrier confinement of the conjugated C₆₀ cluster electrons should serve to enhance the nonlinear optical properties of the solid C₆₀ material near the band edge.

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