Alpha-, Beta-, and Gamma-TODD-G: Novel 2D Planar Carbon Allotropes

TL;DR

This paper introduces three new 2D carbon allotropes with unique structures, stability, and electronic properties, expanding the understanding of potential materials for electronic and optical applications.

Contribution

The study provides a first-principles analysis of alpha-, beta-, and gamma-TODD-G, revealing their stability, electronic behavior, and mechanical and optical properties, which are novel among 2D carbon materials.

Findings

All phases are thermally and dynamically stable.

They exhibit metallic behavior with Dirac-like features.

Optical absorption varies significantly among phases.

Abstract

We present a comprehensive first-principles investigation of three novel two-dimensional carbon allotropes: alpha-, beta-, and gamma-TODD-Graphene (TODD-G), composed of 3-8-12-16, 3-8-12-16, and 3-4-8-12 interconnected carbon rings with sp/sp2 hybridization, respectively. Structural optimization, phonon spectra, and ab initio molecular dynamics simulations confirm their thermal and dynamical stability. All phases exhibit metallic electronic behavior, with distinct Dirac-like features and tilted Dirac cones that suggest anisotropic charge transport. Mechanical analysis reveals tunable anisotropy: alpha-TODD-G is strongly anisotropic, beta-TODD-G shows moderate anisotropy, and gamma-TODD-G displays an almost isotropic mechanical response. Optical spectra further differentiate the phases, with gamma-TODD-G showing strong absorption in the infrared region, while alpha- and beta-TODD-G mainly absorb in the visible and ultraviolet ranges.