Studying Defect Density Distributions in Mixed Perovskites

The immoderate distribution of defects at grain boundaries (GBs), interfaces, and surfaces are dominant factors for highly efficient and stable perovskite solar cells. Here, we introduced an effective way to suppress interfacial defect densities using ionic liquids (ILs; 1-methyl-3-octylimidazolium tetrafluoroborate: C₁₂H₂₃BF₄N₂) as the surface passivation which accelerates the perovskite crystallization via two-step spin coating formed metal halide mixed perovskites without solvent engineering. Using a solid-state electrochemical approach [Ref 1], we measure defect densities for SnO₂/perovskite stacks with or without doping of ILs. To study defect density distributions of passivated and unpassivated SnO₂/perovskite films, the carrier recombination velocities of individual GBs are measured at the microscope scale by mapping the photoluminescence pattern in which changes in nonradiative recombination of carriers at GBs are captured.<br/> <br/>Keywords: <i>Operando characterization</i><i>, Electrochemistry, Mixed perovskite, Surface passivation, solar cells.</i><br/> <br/>References<br/>1. Michel De Keersmaecker, Neal R. Armstrong, and Erin L. Ratcliff. "Defect quantification in metal halide perovskites: the solid-state electrochemical alternative." <i>Energy & Environmental Science</i> 14, no. 9 (2021): 4840-4846.