In-depth Characterization Methodology for the Assessment of Passivation Impact in Halide Perovskite Solar Cells

A wholistic characterization approach is introduced, aiming at establishing a link between nano-scale electrical properties and macro-scale device characteristics for the study of interface passivation in perovskite solar cells. IV measurements are combined with admittance spectroscopy (AS) and deep-level transient spectroscopy (DLTS) for the analysis of charge-related performance losses and with Time-of-Flight Secondary Ion Mass Spectrometry (ToFSIMS) to complete the understanding of ionic accumulation at the perovskite interfaces. An increase of both Voc and FF of approximately 10% are shown for a cell with passivated interfaces compared to a non-passivated reference cell, with an absolute efficiency increase of 4%. The higher FF in the passivated sample could be attributed to a lower influence of some ionic species present in the perovskite. Analysis of the DLTS response yields an activation energy of 0.41 eV, which could be attributed to the presence of either trap states or ionic mobile charges in the perovskite bulk or at one of its interfaces. Finally, preliminary ToF- SIMS results showcase different ionic species and how they are distributed in the device.