Owing to the exceptional photovoltaic and optoelectronic
properties
of metal halide perovskites, they have sparked an intensive interest
in the research community. CsPbBr3 perovskite nanocrystals
(NCs) have come into sight due to their versatile properties that
can be achieved through structural modification. While the prior research
on perovskite nanocrystals has focused mainly on tuning optical and
electronic properties, the understanding of their electronic-ionic
kinetics still remains a significant research gap. In this work, we
explore how the size of CsPbBr3 NCs impacts their electronic-ionic
properties by using electrochemical impedance spectroscopy (EIS).
We systematically tune NC size and investigate the resulting dielectric
properties, conductivity, and capacitance. Notably, larger NCs exhibit
anomalous behavior similar to that of perovskite polycrystalline thin
films in the range of 0.4–0.6 V, indicating strong electronic-ionic
coupling. Conversely, smaller NCs display weak electronic-ionic coupling
due to ion localization. Additionally, this study sheds light on the
electronic-ionic behavior of NCs approaching quantum confinement with
a size reduction, suggesting opportunities for defect engineering.
Ultimately, this work will pave the way for developing advanced electronic
devices utilizing perovskite nanocrystals.