Numerical simulation and fabrication of Pb-free perovskite solar cells (FTO/TiO2/Cs3Bi2I9/spiro-MeOTAD/Au)

Recently, lead (Pb)-free perovskite solar cells (PSCs) have received enormous attention and various Pb-free perovskite and perovskite-like materials have been employed as light absorber for photovoltaic applications. Cesium bismuth iodide (Cs3Bi2I9) is stable and less toxic perovskite-like material. Herein, we have simulated Cs3Bi2I9 based Pb-free PSCs with device architecture of FTO/TiO2/Cs3Bi2I9/spiro-MeOTAD/Au using SCAPS-1D software. The influence of thickness of electron transport layer (ETL), hole transport material (HTM) and light absorber layer (Cs3Bi2I9) were investigated. The best simulated Pb-free PSCs exhibited the highest power conversion efficiency of 11.54%. Further, we have prepared thin films of Cs3Bi2I9 and physiochemical properties were examined by X-ray diffraction (XRD) and optical band gap was determined by employing ultraviolet–visible (UV–vis) absorption spectroscopy. We have also fabricated Pb-free PSCs with device structure of FTO/TiO2/Cs3Bi2I9/spiro-MeOTAD/Au. The fabricated Pb-free PSCs device exhibited good open circuit voltage (Voc) of 780 mV with PCE of 1.66%.