Preparation and characterization of poly (3-hexylthiophene) sensitized Ag doped TiO2 nanotubes and its carrier density under solar light illumination

Poly (3-hexylthiophene) sensitized Ag doped TiO2-NTs (P3HT/Ag-TiO2-NTs) have been prepared using the three sequential steps: two step anodization, galvanostatic deposition and spin coating techniques. The morphology and structure of P3HT synthesized by oxidative polymerization with FeCl3 were characterized using NMR, FT-IR, SEM, XRD and optical properties of P3HT were investigated using Uv-Vis technique. The characterization results showed that the P3HT has 64.7%HT-HT configuration, mainly edge-on oriented lamellar structure and the optical band gap of 2.24 eV. Also, the morphology and structure characterization of P3HT/Ag-TiO2-NTs were determined by FE-SEM and XRD. The electrochemical behaviors of P3HT/Ag-TiO2-NTs in acetonitrile electrolyte contained I−/I3− were examined by utilizing Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The EIS results displayed that after the modification with P3HT, the value of charge transfer resistance at − 0.4 V decreases from 514 Ω cm2 to 121 Ω cm2, compared to Ag-TiO2-NTs. Furthermore, the analysis results of EIS and Mott-Schottky for P3HT/Ag-TiO2-NTs under simulated solar light revealed that the charge transfer resistance decreased from 121 Ω cm2 to 51.60 Ω cm2 and the carrier density (ND) increased from 8.69 × 1021 cm− 3 to 70.1 × 1021 cm− 3, compared to the values under the absence of solar light. These indicate that P3HT supplies better photogenerated electron-hole pairs separation and mobility.