In recent decades, two-dimensional (\num{2}D) perovskites have emerged as promising semiconductors for next-generation photovoltaics, showing notable advancements in solar energy conversion. Herein, we explore the impact of alternative inorganic lattice \ce{BX}-based compositions ($\ce{B} = \ce{Ge}$ or \ce{Sn}, $\ce{X} = \ce{Br}$ or \ce{I}) on the energy gap and stability. Our investigation encompasses \ce{BA$_2$MA$_{n-1}$B$_n$X$_{3n+1}$} \num{2}D Ruddlesden-Popper perovskites (for $n = \num{1} - \num{5}$ layers) and \num{3}D bulk \ce{(MA)BX$_3$} systems, employing first-principles calculations with spin-orbit coupling (SOC), DFT-1/2 quasiparticle, and D3 dispersion corrections. The study unveils how atoms with smaller ionic radii induce anisotropic internal and external distortions within the inorganic and organic lattices. Introducing the \ce{BA} spacers in the low-layer regime reduces local distortions but widens band gaps. Our calculation protocol provides deeper insights into the physics and chemistry underlying \num{2}D perovskite materials, paving the way for optimizing environmentally friendly alternatives that can efficiently replace \ce{Pb} with sustainable materials.
Keywords: Metal Halide Perovskites, Density Functional Theory, Structural, Stability, Electronic Properties.
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