Novel Graphene Allotropes Designed by Polymerizing Pyracyclene Molecules

Our detailed first-principles calculations suggest the assembly of dehydrogenated pyracyclene molecules to give novel graphene allotropes with high stabilities. The allotrope with C4 square conjunction connecting neighboring pyracyclene-based motifs is a Dirac semimetal with tunable velocities of the massless Fermion carriers, which could be increased by similar to 7 x 10(5) m/s by tensile strain. Another allotrope with a C6 hexagon as the conjunction unit is semiconducting, which could be a good photovoltaic material due to its 1.20 eV band gap to meet the sunlight absorption and the high charge carrier mobilities of similar to 10(4) cm(2) V-1 S-1 to help suppress recombination of the light-induced electrons and holes. Furthermore, the continuous tuning of its band gap in a wide range by strain and the sponge-like ultrasoft mechanical properties to facilitate strain loading on experiment make it attractive for next-generation nanoelectronics. In addition, the stacked allotrope layers could also find use for lithium-ion battery anodes because of their high Li capacities of 638 and 1117 mAh/g, good charging and discharging kinetics of Li, and moderate average open-circuit voltages, respectively.

Automated summary

Our first-principles calculations suggest the assembly of dehydrogenated pyracyclene molecules can form novel graphene allotropes with high stabilities. These allotropes have the potential for various applications, such as photovoltaic materials, next-generation nanoelectronics, and lithium-ion battery anodes.