Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX₃, X = Cl, Br, I)

Lead halide perovskite nanowires (NWs) are emerging as a class of inexpensive semiconductors with broad bandgap tunability for optoelectronics, such as tunable NW lasers. Despite exciting progress, the current organic-inorganic hybrid perovskite NW lasers suffer from limited tunable wavelength range and poor material stability. Herein, we report facile solution growth of single-crystal NWs of inorganic perovskite CsPbX₃ (X = Br, Cl) and their alloys [CsPb(Br,Cl)₃] and a low-temperature vapor-phase halide exchange method to convert CsPbBr₃ NWs into perovskite phase CsPb(Br,I)₃ alloys and metastable CsPbI₃ with well-preserved perovskite crystal lattice and NW morphology. These single crystalline NWs with smooth end facets and subwavelength dimensions are ideal Fabry-Perot cavities for NW lasers. Optically pumped tunable lasing across the entire visible spectrum (420-710 nm) is demonstrated at room temperature from these NWs with low lasing thresholds and high-quality factors. Such highly efficient lasing similar to what can be achieved with organic-inorganic hybrid perovskites indicates that organic cation is not essential for light emission application from these lead halide perovskite materials. Furthermore, the CsPbBr₃ NW lasers show stable lasing emission with no measurable degradation after at least 8 h or 7.2 × 10⁹ laser shots under continuous illumination, which are substantially more robust than their organic-inorganic counterparts. The Cs-based perovskites offer a stable material platform for tunable NW lasers and other nanoscale optoelectronic devices.