New lead-free perovskite RbBiCl nanocrystals with blue luminescence and excellent moisture-stability.

The development of nontoxic and stable all-inorganic perovskite nanocrystals (NCs) represents a major challenge to unlock widely practical applications in photoelectric fields. It is an effective strategy to discover nontoxic metal perovskite nanocrystals (NCs) with excellent optical properties. In addition, it has been proved that alkali metals such as rubidium (Rb) and potassium (K) have a good influence on improving the optical performance of perovskites. Hence, we reported new lead-free perovskite Rb7Bi3Cl16 single crystals, which displayed a zero-dimensional cluster structure and were composed of two kinds of octahedra with different distortions. At the same time, we synthesized its NCs, which showed a blue emission at 437 nm with a PLQY of 28.43% and presented a good optical and moisture stability for one month. The excellent moisture-stability might be attributed to their much higher ratio of Rb atoms and the ideal [BiCl6]3- octahedra on the surface, which are beneficial to form an inorganic BiOCl shell to protect the Rb7Bi3Cl16 NCs from moisture attack.