DFT and TDDFT studies of the new inorganic perovskite CsPbI3 for solar cell applications

In this paper, the density functional theory (DFT) and time-dependent density-functional theory (TDDFT) have been used to study the structural, electronic and optical properties of the inorganic perovskite CsPbI3 material. This compound has its applications in the solar cell solicitations. The CsPbI3-based perovskite solar cell (PSC) device has high efficiency together with improved stability. Special attention is paid, in this work, to the effect of spin orbit coupling on the electronic and optical performance of this compound. Using GGA-PBESol method, it is shown that the energy gap value decreases with Spin orbit coupling. In fact, when applying the GGA-PBESol method without SOC approximation, we found a band gap energy value of 1.16 eV. When adding the SOC correction, it is found that the band gap energy value decreases to reach the value 0.39 eV. On the other hand, the studied system exhibits a high absorption in the visible region of the electromagnetic radiations. We studied the effect of GGA-PBESol method with and without Spin orbit coupling, and found that the effect of adding the SOC correction is to decrease the energy gap value. In fact, when applying the GGA-PBESol method without SOC approximation, we found a band gap energy value of 1.16 eV. When adding the SOC correction, it is found that the band gap energy value decreases to reach the value 0.39 eV.