Theoretical Prediction of Monolayer BeP2O4H4 with Excellent Nonlinear‐Optical Properties in Deep‐Ultraviolet Range

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 40; pp. e2404155 - n/a
• Main Authors: Liu, Xin, Wu, Li‐Ming, Kang, Lei, Lin, Zheshuai, Chen, Ling
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.10.2024
• Subjects: 2D materials; deep‐ultraviolet nonlinear optical materials; Energy gap; material deformation monitoring; Monolayers; Nonlinear optics; Optical properties; Tetrahedra; Two dimensional materials
• DOI: 10.1002/smll.202404155
• ISSN: 1613-6810; 1613-6829

Most 2D nonlinear optical (NLO) materials do not have an ultrawide bandgap, therefore, they are unsuitable for working in the deep‐ultraviolet spectral range (< 200 nm). Herein, the theoretical prediction of an excellent monolayer BeP2O4H4 (ML‐BPOH) is reported. DFT analyses suggest a low cleavage energy (≈45 meV per atom) from a naturally existed bulk‐BPOH material, indicating feasible exfoliation. This novel 2D material exhibits excellent properties including an ultrawide bandgap (Eg) of 7.84 eV, and a strong second‐order nonlinear susceptibility (dbulkeff$d_{bulk}^{eff}$ = 0.43 pm V−1), which is comparable to that of benchmark bulk‐KBBF crystal (d16 = 0.45 pm V−1). The wide bandgap and large SHG effect of ML‐BPOH are mainly derived from the (PO2H2)− tetrahedron. Notably, ML‐BPOH exhibits an outstanding 50% variation in dsheet under minor stress stimuli (±3%) due to rotation of structurally rigid (PO2H2)− tetrahedron. This indicates significant potential for application in material deformation monitoring. The theoretical prediction of an excellent DUV SHG 2D material, monolayer BeP2O4H4 (ML‐BPOH) characterized by a low cleavage energy from a naturally existing bulk‐BPOH is reported. Notably, ML‐BPOH exhibits an outstanding 50% variation in dsheet (Å·pm V−1) under minor stress stimuli (±3%), indicating a potential for application in material deformation monitoring.