Dynamic exciton-to-dopant energy transfer tuning of Mn2+-Doped perovskite nanocrystals by PBG effect

Cesium lead halide perovskite nanocrystals (CsPbX 3 NCs) doped with Mn 2+ brings attractive long-wavelength emission and flexible color tunability. However, modulating the exciton-to-Mn 2+ energy transfer efficiency poses a challenge, particularly when relying on traditional methods such as changing halogen composition or incorporating external cations, which often complicate the process. In this work, a simple photonic bandgap (PBG)-modulation strategy is applied to modulate the exciton-to-Mn 2+ energy transfer by constructing a sandwich “PC-Perovskite-PC” structure with two photonic crystal (PC) films and Mn 2+ doped CsPb(ClBr) 3 NPs. When the PBG and the host emission band change from deviation to coincidence, the lifetime of Mn 2+ decreases from 0.54 ms to 0.36 ms owing to the enhancing energy transfer efficiency by PBG effect. Meanwhile, the ratios of orange and blue emissions (O/B) increase from 1.36 to 1.6. In addition, the back energy transfer also can be modulated. When the PBG matches well with the Mn 2+ emission band, the lifetime of the host emission exhibits the largest value (1.25 ns) owing to back energy transfer from Mn 2+ the host. Meanwhile, the O/B value shows the smallest value (0.52) attributed to the decreased spontaneous radiation of Mn 2+ and the enhanced host emission. When PBG deviates from the Mn 2+ emission band, the lifetime of the host emission decreases but O/B value increases gradually. This work provides new strategy for the modulation of energy transfer in Mn 2+ doped CsPb(ClBr) 3 NPs.