Enhancement of Exciton‐Polaron Transport in CsSnBr ₃ Perovskite Nanowires via Lateral Size Engineering

Polarons arising from exciton‐phonon coupling (EPC) largely govern the carrier transport and device performance of functional materials, especially in soft lattices halide perovskites. To date, precise control of EPC for specific halide perovskites components is still limited. Size confinement could modulate EPC in low‐dimensional materials, yet its role in quasi‐1D meso‐scale nanowires remains unclear. Here, we reported an effective modulation of exciton‐polaron dynamics in meso‐scale CsSnBr 3 nanowires via lateral size engineering. With reduced lateral sizes, we observed a significant increase in the exciton emission ratio and a remarkable enhancement (up to 240%) in exciton‐polaron diffusion length, which attributed to the synergistic effect of reduced EPC and enhanced dimensional confinement. Femtosecond transient absorption spectroscopy reveals an ultrafast exciton‐polaron interconversion equilibrium (∼16 ps), confirming the critical role of polaron formation in carrier transport. These findings establish a versatile strategy for controlling exciton‐polaron competition, offering new design principles for high‐performance optoelectronics.