Issue 44, 2020

Stable puckered C2N2 nanosheet with giant anisotropic hole carrier mobility: insights from first-principles

Abstract

Very recently, a black-phosphorus-like nitrogen (bp-N) bulk has been synthesized in high-pressure experiments [D. Laniel, et al., Phys. Rev. Let., 2020, 124, 216001 and C. Ji, et al., Sci. Adv., 2020, 6, eaba9206]. However, the corresponding bp-N monolayer, i.e. a puckered N nanosheet, is unstable, which will decompose to loose N zigzag lines. Based on first-principles calculations, we find that the puckered geometry can be stabilized by inserting C2 dimers between the upper and lower N zigzag lines. The formed C2N2 nanosheet possesses good energetic, dynamical, mechanical, thermal and chemical stabilities, which can maintain the free-standing state even in the presence of O2 gas. Owing to the phosphorene-like geometrical character, this C2N2 nanosheet exhibits an auxetic mechanical behaviour with a negative Poisson's ratio in the out-of-plane direction. The C2N2 nanosheet is an indirect-gap semiconductor with a noticeable linear dichroism. More interestingly, a giant anisotropy appears in the hole mobility of the C2N2 nanosheet, which has a high (low) hole mobility of about 1700 (20) cm2 Vāˆ’1 sāˆ’1 along the armchair (zigzag) direction. The corresponding anisotropic ratio is as large as 85 in the C2N2 nanosheet, which is the maximum mobility anisotropy reported in two-dimensional materials. The high hole mobility and large anisotropic ratio are also preserved in the multilayer C2N2 nanosheets. Our study demonstrates that the puckered N-based nanosheets possess robust structural stabilities and unconventional physical properties, which endow the system with many potential applications in flexible electronics, optoelectronics, and direction-sensitive sensors.

Graphical abstract: Stable puckered C2N2 nanosheet with giant anisotropic hole carrier mobility: insights from first-principles

Supplementary files

Article information

Article type
Paper
Submitted
11 Aug. 2020
Accepted
29 Sept. 2020
First published
02 Okt. 2020

J. Mater. Chem. C, 2020,8, 15655-15663

Stable puckered C2N2 nanosheet with giant anisotropic hole carrier mobility: insights from first-principles

Y. Wang and Y. Ding, J. Mater. Chem. C, 2020, 8, 15655 DOI: 10.1039/D0TC03814H

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