Polymer-Assisted Nucleation for Stable Single-Crystal Perovskite Thin Films

Organic-inorganic hybrid perovskite single crystals have emerged as a strong candidate in photovoltaic and general optoelectronic applications. However, the high supersaturation of the precursor solution leads to the rapid formation of a significant number of nuclei and a diminished concentration of perovskite solute. Consequently, the inadequate availability of precursors poses challenges in sustaining the subsequent crystal growth phase, culminating in the development of small-sized single crystals. In this work, we report a controlled nucleation process to foster the growth of large-size single crystals. This method through the coordination interaction between polyacrylic acid and Pb²⁺ ions, and substitution of the coordination with I⁻ ions. This reduces the formation of the Pb-I₆ complex, which promptly emerges in a state of supersaturation and acts as a nucleus, thereby effectively reducing the number of nuclei formed. The single crystals produced using this method exhibit a lateral size exceeding 5 mm, an extended absorption range, a longer carrier lifetime of 10.93 ns, and enhanced stability. These crystals demonstrate the ability to remain stable even after storage in an ambient environment (T=20±5 °C, RH=60±5 %) for a period of 20 days.