Effect of MgO-coated TiO2 thin film on ITO/TiO2/MEH–PPV/Au solar cells

In this study, the effects of magnesium oxide-coated titanium dioxide (MgO–TiO2) thin film on the performance of ITO/TiO2/MEH–PPV/Au solar cells were investigated. The ITO/MgO–TiO2/MEH–PPV/Au solar cells were fabricated using nano-porous MgO–TiO2 layer infiltrated with poly (2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) (MEH–PPV) to form an active layer on the solar cells. The TiO2 films were prepared by a sol-gel dip-coating technique onto indium tin oxide (ITO) coated glass substrates. To vary the MgO loading content, the TiO2 films were dip-coated in 1 × 10−1, 1 × 10−2, 1 × 10−3, 1 × 10−4 and 1 × 10−5 M solutions of magnesium acetate. After sintering at 450 °C, thin insulating MgO layers were formed on the nano-porous TiO2 films. The ITO coated glass and gold (Au) were used as cathode and anode, respectively. The results revealed that the MgO–TiO2 modification increased open circuit voltage, fill factor, and power conversion efficiency of the ITO/TiO2/MEH–PPV/Au solar cells. These improvements resulted from negative shifts of flat-band potentials of the nano-porous TiO2 films once coated with a thin insulating MgO layer. Moreover, the MgO coating was found to improve the life time of the solar cells.