Networking State of Ytterbium Ions Probing the Origin of Luminescence Quenching and Activation in Nanocrystals

Abstract At the organic–inorganic interface of nanocrystals, electron‐phonon coupling plays an important but intricate role in determining the diverse properties of nanomaterials. Here, it is reported that highly doping of Yb 3+ ions within the nanocrystal host can form an energy‐migration network. The networking state Yb 3+ shows both distinct Stark splitting peak ratios and lifetime dynamics, which allows quantitative investigations of quenching and thermal activation of luminescence, as the high‐dimensional spectroscopy signatures can be correlated to the attaching and de‐attaching status of surface molecules. By in‐situ surface characterizations, it is proved that the Yb‐O coordination associated with coordinated water molecules has significantly contributed to this reversible effect. Moreover, using this approach, the prime quencher OH can be switched to CH in the wet‐chemistry annealing process, resulting in the electron‐phonon coupling probability change. This study provides the molecular level insights and dynamics of the surface dark layer of luminescent nanocrystals.