2D janus niobium oxydihalide NbOXY: Multifunctional piezoelectric semiconductor for electronics, photonics, sensing and sustainable energy applications. (February 2023)

• Record Type: Journal Article
• Authors: Su, Tong; Lee, Ching Hua; Guo, San-Dong; Wang, Guangzhao; Ong, Wee-Liat; Cao, Liemao; Zhao, Weiwei; Yang, Shengyuan A.; Ang, Yee Sin
• Is Part Of: Materials today physics. Volume 31(2023)
• Publication Date: 2023-02
• Subjects: DFT simulation -- 2D piezoelectric materials -- Piezoresistance -- Optical properties -- Photocatalytic water splitting; Materials science -- Periodicals; Physics -- Periodicals; Electronic journals; 530.41
• DOI: 10.1016/j.mtphys.2023.101001
• Languages: English
• ISSNs: 2542-5293

Abstract

Abstract: Two-dimensional (2D) niobium oxydihalide NbOI2 has been recently demonstrated as an excellent in-plane piezoelectric and nonlinear optical material. Here we show that Janus niobium oxydihalide, NbO XY (X, Y = Cl, Br, I and X ≠ Y), is a multifunctional anisotropic semiconductor family with exceptional piezoelectric, electronic, photocatalytic and optical properties. NbO XY are stable and flexible monolayers with band gap around the visible light regime of ∼ 1.9 eV. The carrier mobility of NbO XY exhibits an exceptionally strong anisotoropy ratio of ∼ 400, which is larger than most of the anisotropic 2D semiconductors. The exceptionally large deformation potential of NbO XY monolayers leads to strong piezoresistive effect useful for strain sensing application. Inversion symmetry breaking in Janus NbO XY generates sizable out-of-plane d 31 piezoelectric response while still retaining a strong in-plane piezoelectricity. Remarkably, NbO XY exhibits an additional out-of-plane piezoelectric response, d 32 as large as 0.55 pm/V. G0 W0 -BSE calculation further reveals the strong linear optical dichroism of NbO XY in the visible-to-ultraviolet regime. The optical absorption peaks of 14 ∼ 18% in the deep UV regime (5 ∼ 6 eV) outperform the vast majority of other 2D materials. The high carrier mobility, strong optical absorption, sizable built-in electric field and band alignment compatible with overall water splitting further suggest the strengths of NbO XY in solar-to-hydrogen conversion. We further propose a directional stress sensing device to demonstrate how the out-of-plane piezoelectricity can be harnessed for functional device applications. Our findings unveil NbO XY as an exceptional multifunctional 2D semiconductor for flexible electronics, optoelectronics, UV photonics, piezoelectronics and sustainable energy applications. Graphical abstract: Image 1 Highlights: Janus niobium oxyhalide monolayer (NbO XY ) is computational studied via DFT. NbO XY is a multifunctional 2D material with exceptional physical properties. NbO XY exhibits strong piezoelectric and piezoresistive effects. NbO XY optically highly absorbing and compatible with energy conversion application.