Impact of X‐Anions Modified and Defect Density on the Structural, Electronic, Optical, and Solar Cell Performance in Novel Perovskites Sr 3 NX 3 (X = I, Br, and Cl)

The advent of perovskite solar cells (PSCs) presents a significant new avenue for innovation and growth within the field of photovoltaics. Here, X‐anions modified the structural, optoelectronic and solar cell performance of novel Sr 3 NX 3 (X = I, Br or Cl) perovskite which were deeply studied using density functional theory (DFT) under Quantum Espresso framework with the GGA‐PBE approximation along with SCAPS‐1D software. The structural properties showed that the optimized lattice parameters for Sr 3 NI 3 , Sr3NBr 3 , and Sr 3 NCl 3 are 6.30, 6.00, and 5.80 Å, respectively. The research found that all the materials studied behave as semiconductors with a direct energy band gap at the Ґ point. A notable trend was observed where the band gap could be tuned to larger values by replacing iodine (I) with bromine (Br) and chlorine (Cl). Specifically, the band gaps were determined to be 0.69, 1.07, and 1.29 eV for the materials with I, Br, and Cl, respectively. The results indicated that the investigated perovskite possesses excellent intrinsic optical properties, notably its high absorption capacity. In addition, the study demonstrates that the material's optical behavior can be enhanced by substituting the iodine (I) atoms with either bromine (Br) or chlorine (Cl). The analysis of the dielectric function revealed that replacing iodine with bromine in the Sr 3 NI 3 perovskite resulted in the absorption edge moving to a higher energy zone (a blue‐shift) compared to the original pure iodine compound. Moreover, DFT results obtained, including band gap energy, are employed to the proposed architecture of FTO/ZnO/Sr 3 NX 3 /Spiro‐OMeTAD for the investigation of solar cell performance using SCAPS‐1D. The research also explored how changes in the absorber layer's thickness, the concentration of defects, and the material's band gap impact the device's overall performance. The structure of FTO/ZnO/Sr 3 NBr 3 /Spiro‐OMeTAD has the greatest PCE of 27.23% with a J SC of 41.29 mA/cm 2 , FF of 84.29%, and V OC of 0.78V. Besides, the PCE was found at 22.44% and 14.47% for FTO/ZnO/Sr 3 NCl 3 /Spiro‐OMeTAD and FTO/ZnO/Sr 3 NI 3 /Spiro‐OMeTAD architectures, respectively. The findings suggest that Sr 3 NBr 3 is suitable candidate as a Pb‐free material in PSCs. This research provides a broad set of development guidelines for prior experiments to increase PSCs performance.