Electronic properties of a $π$-conjugated Cairo pentagonal lattice: Direct band gap, ultrahigh carrier mobility and slant Dirac cones

Xiaofei Shao; Xiaobiao Liu; Xinrui Zhao; Junru Wang; Xiaoming Zhang; Mingwen Zhao

doi:10.1103/PhysRevB.98.085437

paper

Electronic properties of a $π$ -conjugated Cairo pentagonal lattice: Direct band gap, ultrahigh carrier mobility and slant Dirac cones

arXiv:1808.00619 · doi:10.1103/PhysRevB.98.085437

Abstract

Two-dimensional (2D) lattices composed exclusively of pentagons represent an exceptional structure of materials correlated to the famous pentagonal tiling problem in mathematics, but their $π$ -conjugation and the related electronic properties have never been reported. Here, we propose a tight-binding (TB) model for a 2D Cairo pentagonal lattice and demonstrate that $p$ - $d$ $π$ -conjugation in the unique framework leads to intriguing properties, such as an intrinsic direct band gap, ultra-high carrier mobility and even slant Dirac cones. On the basis of first-principles calculations, we predict a candidate material, 2D penta-NiP $_{2}$ monolayer, derivated from bulk NiP $_{2}$ crystal, to realize the predictions of the TB model. It has ultra-high carrier mobility ( $\sim$ $1 0^{5} - 1 0^{6}$ $c m^{2} V^{- 1} s^{- 1}$ ) comparable to that of graphene and an intrinsic direct band gap of 0.818 eV, which are long desired for high-speed electronic devices. The stability and possible synthetic routes of penta-NiP $_{2}$ monolayer are also discussed.

arXiv comment24 pages, 6 figures

Electronic properties of a π-conjugated Cairo pentagonal lattice: Direct band gap, ultrahigh carrier mobility and slant Dirac cones

Abstract

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Electronic properties of a $π$ -conjugated Cairo pentagonal lattice: Direct band gap, ultrahigh carrier mobility and slant Dirac cones