Comparative study of the optical, structural, and solar cell performance of (MAPbBr3)x(FAPbI3)1-x(MACl)0.33 mixed perovskite solar cells: With and without the passivation layer

The phases formed and crystallinity of the (MAPbBr3)x(FAPbI3)1-x(MACl)0.33 mixed perovskite films with or without n-Octylammonium iodide (OAI, passive layer) were investigated using X-ray diffraction technique. The effects of passivation and MAPbBr3 on the linear optical parameters and emitted colors of the formed films were explored using UV-spectrophotometer and photoluminescence techniques. Films without MAPbBr3 (without and with OAI) have optical band gap value of 1.55 and 1.54 eV, respectively. This value was increased to 1.58 and 1.56 eV as the amount of MAPbBr3 increased to 5% in the case of films without or with OAI, respectively. Film (without OAI) with 5% MAPbBr3 and films (with OAI) with 3 and 5% MAPbBr3 have the highest nonlinear optical parameters in the visible range. The power conversion efficiency (PCE) value increased to its maximum (20.3%) as the film has an OAI layer and is Br ion free.