On-wire axial perovskite heterostructures for monolithic dual-wavelength laser

All-inorganic lead halide perovskites have attracted tremendous attention for their tunable bandgaps, excellent photoluminescence efficiency and robust stability. Here, we report on a direct vapor-phase growth of high-quality CsPbCl₃/CsPbI₃ axial perovskite heterostructure and multi-heterojunction nanowires using a newly developed magnetic-pulling chemical vapor deposition approach. Microstructural characterization and optical investigations reveal that these structures are crystalline with abrupt heterojunctions. Micro-photoluminescence spectra and mapping at the heterojunctions exhibit dual-wavelength emissions at 417 nm and 698 nm, from the adjacent two disparate perovskites, respectively, further demonstrating the formation of unique heterostructures. Additionally, under a focused laser illumination, asymmetrical waveguide behavior along a single CsPbCl₃/CsPbI₃ wire is clearly observed. Taking a step further, we fabricated a monolithic dual-wavelength laser using an on-wire axial perovskite heterostructure and successfully realized blue and red emissions (425.5 nm and 687.4 nm). The capability to synthesize on-wire heterostructures represents a major step toward high-integration optoelectronic circuits and nanophotonics.