An All‐Inorganic Perovskite‐Phase Rubidium Lead Bromide Nanolaser

Rubidium lead halides (RbPbX 3 ), an important class of all‐inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t ≈0.78, all‐inorganic RbPbBr 3 has not been reported. Now, the crystal structure, X‐ray diffraction (XRD) pattern, and band structure of perovskite‐phase RbPbBr 3 has now been investigated. Perovskite‐phase RbPbBr 3 is unstable at room temperature and transforms to photoluminescence (PL)‐inactive non‐perovskite. The structural evolution and mechanism of the perovskite–non‐perovskite phase transition were clarified in RbPbBr 3 . Experimentally, perovskite‐phase RbPbBr 3 was realized through a dual‐source chemical vapor deposition and annealing process. These perovskite‐phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475–540 nm) single‐mode lasing with a high Q of about 2100.