Considering that electron transfer could be responsible for changes in the substrate energy levels because of the charge doping, we analyze the bandgap of the systems (Table ). The HOMO-LUMO energy difference (HL) of intrinsic phosphorene is 1.3 eV, denoting its semiconductor character as reported from previous first-principles calculations (1.4-1.5 eV) . Conversely, carbon fullerenes show HL values in the range of 0.4 to 1.7 eV, which increase as their size increases (see parenthesis in Table ). Upon interaction, HL values of Phos-Fullerene nanostructures decrease up to 1.0 eV (78%) with respect to intrinsic phosphorene, this is increasing the metallic character. The covalent adsorption of fullerenes causes a larger decrease in the bandgap (56-78%). Nevertheless, we can establish a more general relation: