Comparison of Electroluminescence and Photoluminescence Imaging of Mixed‐Cation Mixed‐Halide Perovskite Solar Cells at Low Temperatures

Abstract Halide perovskites have emerged as promising candidates for high‐performance solar cells. This study investigates the temperature‐dependent optoelectronic properties of mixed‐cation mixed‐halide perovskite solar cells using electroluminescence (EL) and photoluminescence (PL) hyperspectral imaging, along with current–voltage analysis. Luminescence images, which are converted to EL and PL external radiative efficiency (ERE) maps, reveal significant changes in the optoelectronic behavior of these devices at low temperatures. Specifically, it is found that a substantial source of heterogeneity in the low‐temperature EL ERE maps below 240 K is related to local charge injection and extraction bottlenecks, whereas PL ERE maps show suppressed nonradiative recombination and significant improvements in efficiency throughout the investigated temperature range. The spatial distribution of ERE and its variation with applied current are analyzed, offering insights into charge‐carrier dynamics and defect behavior. These results reveal that while the perovskite layer exhibits enhanced ERE at low temperatures, charge injection barriers at the interfaces of the perovskite solar cells can suppress EL and degrade the fill factor below 240 K. These findings reveal that a deeper understanding of the performance of perovskite solar cells under low‐temperature conditions is an essential step toward their potential application in space power systems and advanced semiconductor devices.