Effective Decoupling Bulk Conductivity and Surface Electrochemical Stability in Sol-Gel ATO Thin Films: Insights from Electronic Structure and Crystallization Kinetics

Engineering materials that are simultaneously highly conductive and electrochemically robust is a persistent challenge. This work demonstrates a successful strategy to decouple these competing properties in antimony-doped tin oxide (SnO2:Sb, ATO) thin films prepared via a sol–gel method. Systematic Sb-doping enhances electrical conductivity by over 3 orders of magnitude, with only a minimal 5% trade-off in corrosion resistance. A comprehensive X-ray diffraction analysis with Rietveld refinement reveals the microstructural origin of this behavior: Sb acts as a dual-role agent, simultaneously promoting crystallization (reducing the amorphous content from 39.1% to 17.1%) and inhibiting grain growth (reducing the crystallite size from 65.4 to 41.4 nm). This structural analysis also experimentally validates major first-principles Density Functional Theory (DFT) predictions, such as significant lattice expansion. The DFT simulations rationalize the decoupled properties, revealing that Sb induces bulk metallization while increasing the surface’s intrinsic nobility (work function). The study concludes that the performance is governed by these quantified microstructural changes, offering a validated pathway for designing multifunctional electrodes.