New narrow band gap of silicon-based perovskite FASiI3 for photovoltaic applications: first principle investigations of the structural, electronic and optical properties

Lead-free perovskites are among compounds that are currently most investigated for their potential application in photovoltaic due to their non-toxic effect on the environment. In this paper, we are studying the hybrid organic–inorganic lead-free perovskite FASiI3. The material has been examined using the density functional theory (DFT) and the time-dependent density functional theory (TDDFT). These approaches are implemented in the Quantum Espresso code. In fact, we report the structural and electronic properties of this silicon-based perovskite employing GGA-PBE, GGA-PBESol and LDA approximations. The band structure, the total and partial density of states (DOS and PDOS) of FASiI3 has been presented and discussed, it is demonstrated that this perovskite behaves as a semiconductor with direct bandgap. In addition, we have inspected the spin–orbit coupling impact on the bandgap energy, it is demonstrated that the energy gap reduced with SOC, In fact, we discovered bandgap of 1.33 eV applying the GGA-PBESol approach without SOC. The bandgap energy is found to drop to achieve the value 1.10 eV when the SOC correction is added. Moreover, the optical properties were determined and presented. Our results can pave the way to design new efficient and eco-friendly lead-free perovskite solar material for photovoltaic application. Graphical abstract Silicon-based perovskite FASiI3 for photovoltaic application