Coordination Domain Overlap Governs Anomalous Mobility Recovery in InO x /PAA Thin-Film Transistors

Abstract

Polymer blending in oxide semiconductors is widely used but typically degrades mobility, either monotonically or after a peak. Here we report anomalous mobility recovery in InOx/PAA thin-film transistors: increasing PAA from 1 to 3 wt % collapses the mobility from 5.27 to 1.58 cm2 V–1 s–1, yet increasing to 5 wt % rebounds it to 4.05 cm2 V–1 s–1, 2.4 times the pristine value. XPS indicates decoupling from chemical defects, while TEM and C-AFM reveal a threshold evolution of the transport network from connected to fragmented to partially reconnected, consistent with the mobility trend. We propose a coordination-domain-overlap mechanism: PAA-In3+ domains evolve from isolated to partially and then pervasively overlapping, altering the condensation pathway and connectivity of the inorganic network. This work establishes network connectivity as a key design parameter for oxide/polymer semiconductors, providing a route to high-mobility composite films at high polymer contents.