Structural and optoelectronic properties of 2D halide perovskites Cs2MBr4 (M = Zn, Cd, Hg): a first principle study

• Published in: Optical and quantum electronics 2024-04, Vol.56 (5), Article 871
• Main Authors: Nawab, Gul, Rahman, Ata Ur, Haq, Izaz Ul, Ali, Akbar, Abdelkader, Atef, Ismail, Abd Haj, Alomar, Muneerah, Khan, Imad
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Computer Communication Networks; Electrical Engineering; Lasers; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy
• ISSN: 1572-817X; 1572-817X
• DOI: 10.1007/s11082-024-06710-2

Electronic band structures, density of states, optical parameters, and structure properties of 2D layered halide perovskites Cs 2 MBr 4 (M = Zn, Cd, Hg) are investigated using density functional theory (DFT). The structure optimization/relaxation was executed by generalized gradient approximation (GGA) and to handle band gap dependent properties (optical and electronic) modified Becke Johnson (GGA-mBJ) exchange potential was operated. In the structure composition of Cs 2 MBr 4 , the metal cations (M = Zn, Cd, Hg) build an isolated tetrahedra with bromine atoms i.e. [MBr 4 ] 2− . Eleven Cs atoms confine the tetrahedra and each Cs is surrounded by six tetrahedra, making an octahedral geometry [MBr 4 ] 6 2− . The calculated tolerance factors are greater than unity, confirming their orthorhombic crystal symmetry because perovskites having τ > 1 and large A-site cation destroy the 3D crystal structure. The bonds between octahedral layers are open and A-site (large-sized) cations connect two adjacent octahedra through intermolecular forces to form 2D- perovskite. The understudied 2D layered halide perovskites possess direct band gap nature and their band gap lies between 2.5–3.80 eV. The valence band edge is mainly attributed to M-d, M-s, and Br-4p orbitals, whereas the conduction band is dominated by M-s and Br-4p orbitals. The optical properties tell that these 2D perovskites are excellent dielectric and are prospective materials for optoelectronic devices.