Reentrant semiconducting behavior in polymerized fullerite structures with increasing sp-carbon content.

The electronic behavior of polymerized fullerite structures, ranging from one-dimensional to three-dimensional polymers, was studied using density functional theory with the hybrid Heyd-Scuseria-Ernzerhof functional and a 6-31G(d,p) basis set. The bandgap across these structures decreases with the rise of sp-carbon content until metallic behavior is observed. A further increase induces a reopening of the bandgap, revealing a reentrant semiconducting behavior in this class of materials. This behavior is understood in terms of the new electronic states originated by polymeric bonding and the effect of the volume reduction on the dispersion of sp-states. This study highlights the fullerite polymers as a magnificent platform to tune electronic properties.