Enhanced performance of hybrid photovoltaic devices via surface-modifying metal oxides with conjugated polymer

In this paper, TiO2 nanorods surface was functionalized with poly(1-methoxy-4-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH-PPV), offering a hybrid nanocomposite (MEH-PPV–TiO2 NRs) that was directly applied for the preparation of active layer in hybrids photovoltaic devices. Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM) and photophysical properties verified that the intimately contact between the polymer chains and TiO2 nanorods, by removing the surfactants originally on the TiO2 nanorod surfaces. The performance of the MEH-PPV–TiO2 NRs photovoltaic devices was investigated by current–voltage (J–V) characteristics and intensity modulated photovoltage spectroscopy (IMVS), in comparison to the device based on the blend (MEH-PPV/TiO2 NRs) that was prepared by a conventional mixing process. Results showed that the device performance of the MEH-PPV–TiO2 NRs composite was greatly enhanced, and the power conversion efficiency under monochromic illumination (470 nm, 15.8 mW/cm2) was improved by –30% with respect to the device based on the MEH-PPV/TiO2 NRs counterpart, giving an optimized device performance of a short-circuit current density of 0.45 mA/cm2, an open-circuit voltage of 0.65 V and a power conversion efficiency of 0.10% under simulated AM1.5 illumination (100 mW/cm2). It was also demonstrated that there was a suitable concentration (ca. 17 mg/mL) of the hybrid dispersion for the fabrication of effective devices.