Wavelength-tunable deep blue emission from pure bromide-based colloidal perovskite nanocrystals

Metal halide perovskites are promising light emitters due to their tunable and highly pure emission color in visible light. However, achieving deep blue emission remains a major challenge due to low stability and intrinsic defects. Traditional methods for synthesizing blue-emitting colloidal perovskite nanocrystals (PNCs) involve organic ammonium engineering and halide engineering, which often suffer from problems such as ion migration and color instability. In this study, we demonstrate a novel central metal engineering approach that achieves deep blue emission with a wavelength of 435.8 nm from pure bromide-based PNCs at room temperature. To synthesize deep blue-emitting pure-bromide-based PNCs, we incorporate manganese bromide (MnBr2) to the formamidinium-guanidinium lead bromide (FA0.9GA0.1PbBr3) PNCs. Mn2+ suppresses the growth of FA0.9GA0.1PbBr3 crystals during the synthesis, resulting in decreases in both particle size and dimensionality and deep blue emission by the quantum confinement effect. The emission wavelength of pure-bromide-based PNCs is controlled by varying the amount of MnBr2. This study provides an effective and simple method for achieving deep blue emission from pure bromide-based PNCs, offering significant advantages for display technologies such as light-emitting diodes.