Facile Synthesis of Highly Emissive All-Inorganic Manganese Bromide Compounds with Perovskite-Related Structures for White LEDs.

Lead-free all-inorganic halide materials with different Mn 2+ -based crystal structures (Cs 3 MnBr 5 and CsMnBr 3 ) were obtained using a convenient synthetic method. Cs 3 MnBr 5 had a bright green emission (522 nm), with a unique single-exponential lifetime (τ avg = 236 µs) and a high photoluminescence quantum yield (82 ± 5%). A red emission was observed in the case of the CsMnBr 3 structure with a two-exponential fluorescence decay curve, and the lifetime was 1.418 µs (93%) and 18.328 µs (7%), respectively. By a judicious tuning of the synthetic conditions, a mixed phase of Cs 3 MnBr 5 /CsMnBr 3 was also produced that emitted white light, covering almost the entire visible spectrum. White-light-emitting diodes (WLEDs) with color coordinates (0.4269, 0.4955), a color temperature of (3773 K), and a color rendering index (68) were then fabricated using the as-prepared powder of mixed phases of Cs 3 MnBr 5 /CsMnBr 3 with a commercial UV LED chip (365 nm).