Interface engineering and defect passivation for enhanced hole extraction, ion migration, and optimal charge dynamics...

The study elucidates the potential benefits of incorporating a BiI₃ interfacial layer into perovskite solar cells (PSCs). Using MAPbI₃ and MAGeI₃ as active layers, complemented by the robust TiO₂ and Spiro-OMeTAD as the charge-transport-layers, we employed the SCAPS-1D simulation tool for our investigations. Remarkably, the introduction of the BiI₃ layer at the perovskite-HTL interface significantly enhanced hole extraction and effectively passivated defects. This approach minimized charge recombination and ion migration towards opposite electrodes, thus elevating device performance relative to conventional configurations. The efficiency witnessed a rise from 19.28 to 20.30% for MAPbI₃ and from 11.90 to 15.57% for MAGeI₃. Additionally, MAGeI₃ based PSCs saw an improved fill-factor from 50.36 to 62.85%, and a better J_sc from 13.22 to 14.2 mA/cm², signifying reduced recombination and improved charge extraction. The FF for MAPbI₃ based PSCs saw a minor decline, while the V_oc slightly ascended from 1.24 to 1.25 V and J_sc from 20.01 to 21.6 mA/cm². A thorough evaluation of layer thickness, doping, and temperature further highlighted the critical role of the BiI₃ layer for both perovskite variants. Our examination of bandgap alignments in devices with the BiI₃ interfacial layer also offers valuable understanding into the mechanisms fueling the observed improvements.