Efficient Hot Carrier Management in Lead Halide Perovskite Micro-Disks Revealed by Super-Diffusive Migration

Metal halide perovskites exhibit exceptional optoelectronic properties arising from their defect tolerance, high absorption coefficient, tunable bandgap, and long-range charge transport. The soft crystal structure and interaction with light lead to a number of interesting observations over the years. Here, we investigate carrier migration in anti-solvent-assisted grown methylammonium lead bromide (MAPbBr₃) micro-disks (MDs) using spatially resolved photoluminescence (PL) lifetime microscopy. Confocal excitation reveals rapid outward carrier migration accompanied by pronounced non-linear PL spatial broadening, indicative of super-diffusive carrier migration. Under deep conduction band excitation at 375 nm, carriers exhibit accelerated diffusion over hundreds of nanometers on an ultra-stable nanosecond timescale, with diffusivity increasing from initial average values of ∼0.44 cm²/s to equilibrium values exceeding 0.88 cm²/s. The degree of non-linearity, represented by an average non-linearity coefficient of 1.5, signifies strong deviation from classical diffusion. Comparative measurements with 485 nm excitation, temperature-dependent studies, and analysis of diffusivity gain and non-linearity demonstrate that these dynamics originate from stabilized hot carriers interacting with low-energy LO phonon modes through large-polaron formation. The observation of nanosecond-scale super-diffusion in perovskite microstructures highlights efficient hot-carrier transport, with implications for designing high-performance optoelectronic and hot-carrier energy-harvesting devices.