Design Rules for Perovskite Nanocrystals: Volume‐Governed Absorption Versus Shape‐Controlled Auger Recombination

Abstract Understanding the interplay between morphology and optical properties in lead halide perovskite nanocrystals is critical for advancing optoelectronic applications. In this study, the one‐photon absorption (OPA) cross‐section and biexciton Auger lifetimes of CsPbBr₃ nanocrystals with varying dimensionality, including nanocubes, nanoplatelets, and nanorods, are investigated. Using ultrafast transient absorption spectroscopy, the OPA cross‐section is extracted from fluence‐dependent measurements and the decay dynamics of excitonic states are examined. The results reveal that the OPA cross‐section scales linearly with nanocrystal volume, irrespective of morphology, providing the most comprehensive experimental validation of this relationship to date. Furthermore, the universal volume scaling law for biexciton Auger recombination is confirmed in the strong confinement regime, but deviations from it in the weak confinement regime are demonstrated. The biexciton Auger lifetime saturates for nanocrystals with dimensions exceeding the exciton Bohr radius, while nanorods and nanoplatelets exhibit shape‐dependent confinement effects that influence their carrier recombination dynamics. These findings offer valuable insights into the design of perovskite nanocrystals for high‐performance optoelectronic devices, including light‐emitting diodes, lasers, and photodetectors.