Phase Stability, Bandgap correction, and Absorption spectra of highly efficient Tetramethylammonium based Perovskite

Modelling Perovskite for solar cell absorbers has made significant progress recently, resulting in improved theoretical photovoltaic conversion efficiency (PCE). This report models the ground state structure of Pb, Sn, Mg, and Ge-based tetramethylammonium perovskite, considering the spin-orbit coupling effect. Similarly, we explore their electronic structure, thermodynamic stability, and optical absorption spectra. The electronic structure calculations were carried out using the Density functional theory and the GW quasiparticle methods. Similarly, the absorption spectra were calculated from the real and imaginary parts of the dielectric tensor obtained from solving the Bethe-Salpeter equation. The phonon dispersion and density of state reveal the thermodynamic stability of Pb, Sn, and Ge-based perovskite. The reported absorption coefficients were in the order of 10⁶ absorption coefficient, and the spectroscopic limited maximum efficiency reported an increased theoretical power conversion efficiency of about 48%. The high absorption coefficient, high spectroscopic limited maximum efficiency, and low transmittance indicate an exciting prospect for highly efficient non-transparent solar cell absorbers.