Probing Size-Driven Exciton Behavior in InP Tetrapods via Time-Resolved Spectroscopy

Quantum-confined nanocrystals (NCs) have garnered huge attention in various applications due to their unique optoelectronic properties arising from quantum confinement effects. Recently, single-crystalline InP tetrapods have been proposed as an attractive system, allowing modulation from single-photon to multiphoton emission by tuning the size of the tetrapods. Herein, the size-driven exciton behavior in tetrapods is investigated through time-resolved spectroscopy to achieve a fundamental understanding of their unique emission transition. The experimental results reveal that the behavior of excitons and biexcitons exhibits distinct trends with varying sizes, showing a remarkable 4-fold enhancement in the biexciton Auger lifetime as the size increases. Our findings clarify that the transition between single-photon and multiphoton emission arises from a volume effect and the interplay between quantum confinement and Coulomb interactions. This research provides fundamental knowledge of the optical properties of single-crystalline tetrapods and highlights the potential for functional selection in NCs based on size and shape control.