Research Information System
MATERIALS RESEARCH EXPRESS, vol.12, no.11, 2025 (SCI-Expanded, Scopus)
This study presents a systematic investigation into the influence of an optimized multi-step spin-coating process on the structural, optical, and electrical properties of TiO2/multi-walled carbon nanotube (MWCNT) nanocomposite films deposited on indium tin oxide (ITO) substrates. A stable sol was synthesized using polyvinylidene fluoride (PVDF) as a binding agent. Structural characterization via x-ray diffraction (XRD) revealed that the optimized coating process resulted in an increase in the average crystallite size from 65 nm to 74 nm. Field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) analyses showed rough, heterogeneous surfaces with a non-uniform distribution of TiO2 nanoparticles on the MWCNT network. The optical band gap energy was observed to increase from 2.88 eV to 3.06 eV following the additional spin-coating steps, which is attributed to enhanced electron localization and strong interfacial interactions. Current-voltage (I-V) measurements demonstrated non-linear and symmetrical behavior for both samples. The sample prepared with the standard process (TM1) exhibited a higher resistivity of 23.6 k Omega, attributed to defect complexes, while the sample with the optimized process (TM2) showed a lower resistivity of 18.6 k Omega, indicative of improved conductivity facilitated by effective MWCNT pathways and TiO2 incorporation. This conclusion is supported by lower non-linear coefficients (alpha) of 1.85 and 1.52 for TM1 and TM2, respectively, suggesting trap-assisted electron transport governed by the Poole-Frenkel mechanism. The findings confirm that the electrical conductivity and overall optoelectronic performance of TiO2/MWCNT nanocomposites can be significantly enhanced by tailoring the spin-coating parameters, primarily due to improved charge transport and suppressed electron-hole recombination.