Comparative evaluation of charge transport in polyaniline tungsten trioxide graphene nanocomposites deposited on taconic FR4 and silicon substrates

The performance of polymer-based sensors is highly dependent on the selected substrate material, as it plays a crucial role in determining sensor stability, polymer adhesion, and overall signal quality. This work presents a systematic comparative investigation of how substrate selection critically influences the electrical behavior of conducting polymer nanocomposites. Compared to prior studies that investigated Taconic, FR4 (flame retardant-4), or silicon substrates individually, this work presents a direct and systematic comparative analysis of all three substrates for hydrochloric acid (HCl)-doped polyaniline (PANI) nanocomposites reinforced with tungsten trioxide (WO3) and graphene, fabricated using the spin-coating technique. This work demonstrates how substrate-dependent coating thickness and surface morphology control the charge transport, which presents an alternative approach to device optimization. The polyaniline nanocomposites were synthesized via in-situ chemical polymerization with varying filler concentrations and characterized using SEM, TEM, XRD, FTIR, and impedance analysis. The nanocomposites were deposited onto the substrates using spin coating, and the charge transport mechanism was assessed through current–voltage (I–V) measurements. The study shows that both the substrate type and the coating thickness have a substantial impact on electrical conductivity. Among the substrates, FR4 exhibited a minimum conductivity of 2⋅10− 4 S/cm, Taconic showed 9⋅10− 7 S/cm, while the silicon wafer demonstrated the highest conductivity of 1.9⋅10− 3 S/cm at 10 wt% filler concentration, confirming its superior charge transport properties. Although Taconic offers superior microwave properties, its chemically inert surface and weaker adhesion lead to non-uniform coatings, which reduce interfacial charge transport and electrical performance. These results indicate that thinner and smoother coating promotes better electrical conduction. The study affirms that careful choice of substrate and filler optimization are key to achieving superior performance in polymer-based electronic and sensor technologies.