Ideal Strength of Doped Graphene

TL;DR

This study uses first-principles calculations to explore how electronic doping influences the mechanical strength and failure mechanisms of graphene under different strain conditions, revealing doping-dependent stability effects.

Contribution

It provides new insights into the impact of electron and hole doping on graphene's mechanical properties under isotropic and uniaxial strains, clarifying previous experimental-theoretical discrepancies.

Findings

Doping can slightly improve ideal strength under isotropic strain.

Electron doping decreases strength under uniaxial strain, while hole doping increases it.

Different failure mechanisms are identified for isotropic and uniaxial strains.

Abstract

While the mechanical distortions change the electronic properties of graphene significantly, the effects of electronic manipulation on its mechanical properties have not been known. Using first-principles calculation methods, we show that, when graphene expands isotropically under equibiaxial strain, both the electron and hole doping can maintain or improve its ideal strength slightly and enhance the critical breaking strain dramatically. Contrary to the isotropic expansions, the electron doping decreases the ideal strength as well as critical strain of uniaxially strained graphene while the hole doping increases the both. Distinct failure mechanisms depending on type of strains are shown to be origins of the different doping induced mechanical stabilities. Our findings may resolve a contradiction between recent experimental and theoretical results on the strength of graphene.