Structure and Photophysical Properties of Cubic‐Shaped Cadmium(II)‐Doped CsPbBr ₃ Perovskite Nanocrystals

Abstract Bandgap engineering in lead halide perovskites through the lead‐site doping is a promising strategy to achieve blue‐shifted emission in nanocrystals (NCs) without relying on quantum confinement or halide mixing. Here, the structure and photophysical properties of CsPb _1−x Cd _x Br ₃ NCs with a varied amount (3, 8, and 15%) of Cd(II) doping are explored. The incorporation of the increasing amount of Cd ²⁺ ions results in an up to 5 nm decrease of the average NC size, while the emission is blue‐shifted from 515 to 485 nm. Applying the ultrafast transient absorption spectroscopy, a significant enhancement is observed in the absorption oscillator strength of CsPb _1−x Cd _x Br ₃ NCs along with an almost threefold increase in the hot carrier temperature, which indicates more efficient population of the band edge compared to pristine CsPbBr ₃ . Furthermore, it is demonstrated that CsPb _1−x Cd _x Br ₃ NCs exhibit their own volume scaling law for the exciton–exciton annihilation threshold and rate. Specifically, Cd(II)‐doped CsPbBr ₃ NCs with a smaller size exhibit a higher Auger threshold than the larger pristine CsPbBr ₃ NCs, which makes them potentially useful for light‐emitting and lasing applications. The insights gained into the excited carrier dynamics in CsPb _1−x Cd _x Br ₃ NCs open new pathways for the development of efficient nanoscale emitters in the blue spectral range.