Electrical and optical properties of nanohybrid MEH-PPV: Niobium doped TiO2 thin films for organic photovoltaic cells

Titanium dioxide (TiO₂) nanopowders of pure and niobium (Nb) doped TiO₂ were synthesized using a sol gel immersed heater method. The nanopowders were then used as a filler in poly [2-methoxy-5-(2´-ethylhexyloxy)-p-phneylene] (MEH-PPV) to form hybrid organic-inorganic solar cells. In this study, the influence of TiO₂ doped with different concentrations of niobium on the properties of nanohybrid MEH-PPV: TiO₂ thin films have been investigated. Compared with a pristine thin film (undoped TiO₂), the nanohybrid MEH-PPV: doped TiO₂ thin films show an improvement in electrical photoconductivity with increase of niobium concentration. Optical analysis reveals that Nb-doped TiO₂ shows a shift in absorption edge to longer wavelength compared to undoped TiO₂ and exhibited strong absorption at wavelength Of 500 nm in visible and 340 nm in UV ranges respectively. The nanohybrid thin films have an average of 70% transmission in visible region and the energy band gap values using Tauc´s formula have also been estimated.