A first-principles study of 1D and 2D C₆₀nanostructures: strain effects on band alignments and carrier mobility

In the breakthrough progress made in the latest experiment Houet al(2022Nature606507), 2DC60polymer was exfoliated from the quasi-hexagonal bulk crystals. BulkC60polymer with quasi-tetragonal phase was found to easily form 1D fullerene structure withC60molecules connected by C=C. Inspired by the experiment, we investigate the strain behaviors of 1D and 2DC60polymers by first-principles calculations. Some physical properties of these low dimensionalC60polymers, including structural stability, elastic behavior, band alignment and carrier mobility, are predicted. Compared with fullereneC60molecule, 1D and 2DC60polymers are metastable. At absolute zero temperature, 1DC60bears a uniaxial tensile strain less than 11.5%, and 2D monolayerC60withstands a biaxial tensile strain less than 7.5%. At 300 K,ab initiomolecular dynamics confirm that they can withstand the strains of 9% and 5%, respectively. Strain engineering can adjust the absolute position of the band edge. In the absence of strain, carrier mobility is predicted to beµ= 398 andµ= 322cm2V-1s-1for 1DC60polymer, andμe,x=74/μe,y= 34cm2V-1s-1andμh,x=646/μh,y= 1487cm2V-1s-1for 2DC60polymer. Compared with other carbon based semiconductors, theseC60polymers exhibit high effective mass, resulting in low mobility.