Charging C60 islands with the AFM tip

Abstract

We show that electrons can be transferred on demand from an AFM tip into single bulk-like C₆₀ islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T_1u band. The charge dissipates during half a day due to an interaction of the charged C₆₀ islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C₆₀ bulk-like system.