Effect of surface treatment on the photovoltaic properties of titania nanorods and MEHPPV nanocomposites

In this work, anatase titanium dioxide (TiO₂) nanorods (NRs) were synthesized by low-temperature hydrolysis of titanium tetraisopropoxide (TTIP) and using oleic acid (OA) as capping agent. The OA-capped titania NRs were then processed using surface ligand exchange by pyridine (Py). The two types of NRs, with different capping agents hence obtained, were blended with poly[2-methoxy-5-(2′-ethyl-hexyloxy)-l,4-phenylene vinylene] (MEHPPV) to prepare hybrid organic–inorganic nanocomposites. In order to elucidate the changes caused by the surface modifications, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction were used to study the morphology. The Fourier transform infrared spectroscopy (FTIR) analysis confirms that the ligands coordinated with the Ti center of TiO₂ NRs. The optical properties of the modified TiO₂ NRs are characterized by UV–Vis absorption spectra and photoluminescence (PL) spectra. Photoluminescence lifetime studies were conducted to predict the capping agent more suitable for photovoltaic applications.