Electron Localization and Mobility in Monolayer Fullerene Networks

The novel 2D quasi-hexagonal phase of covalently bonded fullerene molecules (qHP C₆₀), the so-called graphullerene, has displayed far superior electron mobilities, if compared to the parent van der Waals three-dimensional crystal (vdW C₆₀). Herein, we present a comparative study of the electronic properties of vdW and qHP C₆₀ using state-of-the-art electronic-structure calculations and a full quantum-mechanical treatment of electron transfer. We show that both materials entail polaronic localization of electrons with similar binding energies (≈0.1 eV) and, therefore, they share the same charge transport via polaron hopping. In fact, we quantitatively reproduce the sizable increment of the electron mobility measured for qHP C₆₀ and identify its origin in the increased electronic coupling between C₆₀ units.