Effect of Sb doping and polyvinylpyrrolidone on the mesoporous TiO2 photoanodes for Sb2Se3 sensitized solar cells

Mesoporous-TiO2:Sb layers were developed by sol-gel and spin-coating techniques for their application as photoanodes in SSSCs. The effect of Sb doping (4 mol%) and PVP loading (0.2-0.4 g) on the optical, structural, morphological, and chemical properties were studied. SEM results showed that the morphology, porosity, and particle size in the mp-TiO2:Sb depend on the amount of polymer and Sb doping. In particular, the doping decreases the porosity and particle size. XRD patterns showed well-defined reflections resembling the anatase crystalline structure. The crystallite size was of 22.61 and 16.27 nm for the undoped layers with 0.2 and 0.4 of PVP, which decreased to 17.69 and 7.93 nm for the doped ones. It was not observed the presence of Sb2O3 or Sb metallic, indicating Sb ions were inserted in the TiO2 lattice by substitution of Ti ions. Analysis of XPS spectra showed the presence of Ti4+, O2-, and Sb3+ in the mp-TiO2:Sb layers. The optical bandgaps of the mp-TiO2:Sb were in the range of 3.14-3.33 eV. The evaluation of the mp-TiO2:Sb layers as photoanodes in the Sb2Se3-sensitized solar cells gives a Voc of 261 mV, a Jsc of 3.92 mA/cm2, and a PCE of 0.71%.