In this research, the ternary non-centrosymmetric chloroperovskites compounds of the form ABCl3 (A = Rb and B = Be, Mg) are investigated extensively to predict the structural, mechanical, and optoelectronic properties with DFT incorporated in WIEN2K code. The crystalline structure of interested chloroperovskites is identified to be cubic, non-centrosymmetric, and stable. The elastic constants Cij, bulk modulus, criteria of Pugh ratio, and the Born criteria confirm the ductility and mechanical stability of ternary RbBeCl3 and RbMgCl3 materials. Electronic properties such as the band structures and density of states are examined with the most widely recognized TB-mBJ potential approximation. RbBeCl3 shows semiconducting behaviour with an indirect wide band gap energy of 3.74 eV from R-Gamma symmetries points, while RbMgCl3 is assumed to be an insulator that possesses indirect wide band gap energy of 6.28 eV from R-Gamma. It is identified that the ABCl3 (A = Rb and B = Be, Mg) non-centrosymmetric compounds change the behavior from wide band gap semiconductors to perfect insulators when the 'B' site in ABCl3 varies from 'Be' to 'Mg' element. In the electromagnetic range from 0 eV to 40 eV of incident photons energy, several parameters in optical properties that includes the dielectric function, refractive index, absorption coefficient, optical conductivity, extinction coefficient, and energy loss function are investigated for the quest of potential applications of interested non-centrosymmetric cubic systems in modern photovoltaic technologies. These outcomes may add inclusive understanding within ultraviolet ranges for photovoltaic applications.
