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 the visible light. However, achieving stable 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. Recently, B-site engineering has been attempted to achieve blue emission from pure halide PNCs. In particular, the research of achieving the emission color of pure bromide-based PNCs to blue by utilizing the quantum confinement effect is actively studied. However, it has a limitation that the emission color of pure bromide-based PNCs cannot be achieved to deep blue. In this study, we demonstrate a novel central metal engineering approach which achieves deep blue emission with a wavelength of 435.8 nm from pure bromide-based PNCs at room temperature for the first time. To synthesize deep blue-emitting pure-bromide based PNCs, we dope manganese cations (Mn²⁺) to the formamidinium-guanidinium lead bromide (FA_0.9GA_0.1PbBr₃) PNCs. Mn²⁺ suppresses the growth of FA_0.9GA_0.1PbBr₃ 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 Mn²⁺. 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.
Acknowledgement
This research was supported by the Digital Research Innovation Institution Program Through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT (RS-2023-00283597).