Core-Shell Perovskite Fibers for Dual Emission and Random Lasing in an Aqueous and Acidic (pH = 3) Medium.

Random lasing (RL) from perovskites is highly attractive for achieving speckle-free imaging owing to its low spatial coherence. However, the intrinsic instability of perovskites limits their practical applications. Here, to overcome this, we encapsulate different metal-halide perovskites in a hydrophobic poly (methyl methacrylate) matrix and fabricate core-shell perovskite composite fibers via coaxial electrospinning. The composite exhibits a uniform distribution of perovskites, resulting in single- and dual-color emitting perovskite fibers. The dual-emissive fibers demonstrate remarkable water resistance, maintaining emission after 9 days. Their emission persists even under combined thermal stress (50 °C) and UV exposure in water for up to 40 min. Notably, the green-emitting core-shell fibers exhibit stable RL behavior in diverse environments, including air, water, and an acidic medium (pH = 3), highlighting their robustness in extreme conditions. Furthermore, RL from these fibers enables speckle-free imaging with an ultralow speckle contrast (K = 0.008), compared to a conventional CW laser.