Persistent Electronic Activation of ZnO Nanocrystal Transistors after LiPF6-Based Electrolyte Treatment

Abstract ZnO is of broad interest because it serves not only as an oxide semiconductor for electronic devices but also as a promising anode material for LIBs, where it operates in direct contact with LiPF6-based electrolytes. Despite this relevance, the purely electronic response of ZnO to such electrolytes has remained largely overlooked. Here, we investigated a simple post-fabrication LiPF6 dipping treatment for ZnO nanocrystal field-effect transistors to isolate the effect of electrolyte exposure on charge transport. The effective trap density estimated from the subthreshold swing decreased from 8.4 × 1012 to 5.1 × 1012 cm−2 eV−1, while the threshold voltage shifted from +8.1 to −1.2 V, corresponding to an equivalent interfacial charge density change of ∼1.0 × 1012 cm−2. These values are physically consistent if the reduced trap states act over an effective energy range of ∼0.30 eV near the transport-relevant band edge. X-ray diffraction, transmission electron microscopy, and atomic force microscopy revealed negligible structural and morphological changes, indicating that the improved transport originates mainly from surface/interfacial electronic modification rather than bulk reconstruction. This work highlights electrolyte-induced electronic activation of ZnO as an overlooked but important phenomenon relevant to both oxide electronics and ZnO-based LIB interfaces.