Unveiling the Importance of Lead Halide Perovskite Precursor Purity and Its Impact on Stability

Perovskite precursor purity plays a crucial role in determining the characteristics and stability of perovskite solar cells (PSCs). This study systematically investigates the influence of precursor impurity levels on the material properties and device performance. High-purity precursors enhance grain growth and suppress the intermediate phase formation. Thermogravimetric analysis (TGA) confirms that low-impurity precursors exhibit an enhanced thermal stability. Electrical and optical characterizations reveal that reduced impurity content suppresses current-voltage hysteresis and nonradiative recombination. Sodium (Na) is identified as a dominant impurity, and its reduction enhances the thermal stability. Devices fabricated with low-impurity precursors achieved a power conversion efficiency of 20.15% and maintained 96.7% of their initial efficiency after two months of ambient exposure, whereas higher-impurity devices experienced significant degradation. This study establishes precursor purity as a key determinant of PSC efficiency and stability, offering insights into the advancement of stable and efficient photovoltaic devices.