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Ab initio calculations for the Linear Macroscopic Dielectric analyses of CH3NH3BiBr3 and CH3NH3GaBr3 (having 8.33% dopant replacement percentage each) as possible replacements for the Lead based perovskite CH3NH3PbBr3 were done in this work using Perdew-Burke-Ernzerhof functional of Density Functional Theory as implemented by FHI-aims Code. Optimized lattice constants were calculated for CH3NH3BiBr3 and CH3NH3GaBr3 to be 9.10 Å and 8.27 Å respectively. The Lowest Unoccupied Molecular Orbital (LUMO), Highest Occupied Molecular Orbital (HOMO) and calculated band gap, Band Structure and Density of States (DOS) plots were made to analyse the band structures of these crystals and they were found to be metallic with a band gap of 0.00018636 eV and 0.00022286 eV for CH3NH3BiBr3 and CH3NH3GaBr3 respectively. The imaginary and real parts of the inter-band and intra-band contribution to the linear dielectric tensor within the e imagi Random Phase Approximation (RPA) of the optical properties of these perovskites were calculated and an average dielectric tensor of 3.1209467 and 2.789173 was found for CH3NH3BiBr3 and CH3NH3GaBr3 respectively. From the absorption data and dielectric tensor components calculated, both materials have an average absorption peak at frequency of 16.5373nm at 1.006567 MeV, 16.2040nm at 1.227600 MeV respectively, across all cubic planes. [ABSTRACT FROM AUTHOR]

RbVO 3 luminescent materials have been successfully prepared by solid-state synthesis. The phase, surface morphology and photoluminescence properties of RbVO 3 have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and luminescence spectrophotometer, respectively. The band structure, Density of States and optical properties of RbVO 3 have been simulated by Materials Studio software based on density functional theory (DFT). According to the experimental results and the First-principles, the electronic structure and optical properties of RbVO 3 were studied. The results show that RbVO 3 crystal has a direct band gap with a band gap of 2.973 eV. Under ultraviolet excitation in the range of 210–390 nm, and the excitation spectrum peak appears at 340 nm. The emission spectrum of RbVO 3 phosphors ranges from 400 to 700 nm, and its peak emission spectrum is near 507 nm, showing white luminescence emission. • RbVO 3 has been successfully prepared by solid-state synthesis. • The RbVO 3 luminescent material is a high brightness phosphor. • PL measurements on RbVO 3 shows a broad emission centered at 507 nm. • The optical properties of RbVO 3 are studied in detail based on first-principles for the first time. • The band structure, density of States and optical properties of RbVO 3 were calculated to reveal its luminescence mechanism. [ABSTRACT FROM AUTHOR]