High-Quality In-Plane Aligned CsPbX₃ Perovskite Nanowire Lasers with Composition-Dependent Strong Exciton–Photon Coupling

Cesium lead halide perovskite nanowires have emerged as promising low-dimensional semiconductor structures for integrated photonic applications. Understanding light–matter interactions in a nanowire cavity is of both fundamental and practical interest in designing low-power-consumption nanoscale light sources. In this work, high-quality in-plane aligned halide perovskite CsPbX3 (X = Cl, Br, I) nanowires are synthesized by a vapor growth method on an annealed M-plane sapphire substrate. Large-area nanowire laser arrays have been achieved based on the as-grown aligned CsPbX3 nanowires at room temperature with quite low pumping thresholds, very high quality factors, and a high degree of linear polarization. More importantly, it is found that exciton–polaritons are formed in the nanowires under the excitation of a pulsed laser, indicating a strong exciton–photon coupling in the optical microcavities made of cesium lead halide perovskites. The coupling strength in these CsPbX3 nanowires is dependent on the atomic composition, where the obtained room-temperature Rabi splitting energy is ∼210 ± 13, 146 ± 9, and 103 ± 5 meV for the CsPbCl3, CsPbBr3, and CsPbI3 nanowires, respectively. This work provides fundamental insights for the practical applications of all-inorganic perovskite CsPbX3 nanowires in designing light-emitting devices and integrated nanophotonic systems.