On the Use of Luminescence Intensity Images for Quantified Characterization of Perovskite Solar Cells: Spatial Distribution of Series Resistance

Perovskite solar cells (PSCs) have made rapid advances in efficiency when fabricated as small-area devices. A key challenge is to increase the active area while retaining high performance, which requires fast and reliable measurement techniques to spatially resolve cell properties. Luminescence imaging-based techniques are one attractive possibility. A thermodynamic treatment of the luminescence radiation from MAPbI₃ and related perovskite semiconductors predicts that the intensity of luminescence emission is proportional to the electrochemical potential in the perovskite absorber, bringing with it numerous experimental advantages. However, concerns arise about the impact of the often-observed hysteretic behavior on the interpretation of luminescence-based measurements. This study demonstrates that despite their hysteretic phenomena, at steady-state perovskite solar cells are amenable to quantitative analysis of luminescence images. This is demonstrated by calculating the spatial distribution of series resistance from steady-state photoluminescence images. This study observes good consistency between the magnitude, voltage-dependence, and spatial distribution of series resistance calculated from luminescence images and from cell-level current–voltage curves and uncalibrated luminescence images, respectively. This method has significant value for the development of PSC process control, design and material selection, and illustrates the possibilities for large-area, spatially resolved, quantitative luminescence imaging-based characterization of PSCs.