Diameter Control and Optical Properties of CsPbBr ₃ Nanowires Based on the Oleylamine–Octylamine System

Metal halide perovskites (MHPs) have emerged as prominent materials in optoelectronics due to their exceptional photoelectric conversion efficiency and tunable band structures. Traditional perovskite nanocrystal synthesis systems often employ oleic acid (OA) to accelerate the crystallization kinetics, which inadvertently hinders nanowire growth and morphology control. In this study, we adopted a dual-ligand system using oleylamine (OAm) and octylamine (OctAm) without preadding OA. By postinjecting a cesium oleate solution, we achieved precise control over Pb2+ ion release, enabling the controllable synthesis of cesium lead halide (CsPbBr3) nanowires (NWs) across 100–160 °C. This strategy yielded micrometer-scale NWs with tunable diameters (8.3–12.6 nm) and lengths reaching the microscale. Temperature-dependent optical studies revealed that elevated synthesis temperatures weakened quantum confinement effects, leading to systematic red-shifts in ultraviolet–visible (UV–vis) absorption (505–507 nm) and photoluminescence (PL) emission (516–518 nm) peaks. Concurrently, time-resolved PL measurements revealed a significant enhancement in carrier lifetime (24.72–91.99 ns), reflecting reduced nonradiative recombination pathways. Variable-temperature PL spectroscopy (80–300 K) demonstrates that CsPbBr3 NWs synthesized at 140 °C exhibit higher exciton binding energy (Eb = 44.7 meV) and enhanced exciton–phonon coupling strength (ΓOP = 46.48 meV) compared to samples prepared at 120 °C. These findings demonstrate that high-temperature synthesis confers superior thermal stability on CsPbBr3 NWs. Our work not only clarifies the critical role of amine ligands in modulating NW growth dynamics but also provides a robust framework for designing stable, high-performance, one-dimensional perovskite optoelectronic materials.